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Graphene FET Gigabit On-Off Keying Demodulator at 96 GHz
Abstract
We demonstrate the demodulation of a multi-Gb/s ON-OFF keying (OOK) signal on a 96 GHz carrier by utilizing a 250-nm graphene field-effect transistor as a zero bias power detector. From the eye diagram, we can conclude that the devices can demodulate the OOK signals up to 4 Gb/s.
... Regarding radiofrequency modulators based on GFETs, there have been some proof-of-concept demonstrations working within the kHz range and using one single device but without any circuit design strategies for improving matching and/or stability conditions [10,11]. The only GHz modulators based on any emerging technology have been demonstrated with GFETs in [12] (on-off keying at 96 GHz) and [13] (ASK and PSK at 90 GHz) obtained with zero-bias device conditions, i.e., V DS = 0. Hence, these pure resistive GFET-based designs exploit the inherent high mobility of the graphene channel but yield a poor performance in terms of output power due to the lack of gain. ...
... The latter implies less production costs and a smaller chip area (if the stability network is properly designed). In contrast to the passive GFET-based modulators found in the literature [10][11][12], this PSK circuit presents an AC gain of ∼1.5 V/V and ∼1.3 V/V at the ON and OFF state of the baseband pulses, respectively. As a further verification figure of merit, the V GS dependence of the phase of v out is also shown in Figure 6. ...
The multifunctionality feature of graphene field-effect transistors (GFETs) is exploited here to design circuit building blocks of high-data-rate modulators by using a physics-based compact model. Educated device performance projections are obtained with the experimentally calibrated model and used to choose an appropriate improved feasible GFET for these applications. Phase-shift and frequency-shift keying (PSK and FSK) modulation schemes are obtained with 0.6 GHz GFET-based multifunctional circuits used alternatively in different operation modes: inverting and in-phase amplification and frequency multiplication. An adequate baseband signal applied to the transistors’ input also serves to enhance the device and circuit performance reproducibility since the impact of traps is diminished. Quadrature PSK is also achieved by combining two GFET-based multifunctional circuits. This device circuit co-design proposal intends to boost the heterogeneous implementation of graphene devices with incumbent technologies into a single chip: the baseband pulses can be generated with CMOS technology as a front end of line and the multifunctional GFET-based circuits as a back end of line.
... Hence, most of the reported GFET-based circuits exploit the change in channel resistance (R ds ) with gate-source voltage rather than its transconductance (g m ). Examples are reported FET-resistive mixers in [4]- [7], frequency multiplier in [8], and power detectors in [9] and [10]. A graphene radio frequency (RF) receiver has been reported [11] at 4.3 GHz employing a three-stage GFET-based amplifier by using the last stage as a down-conversion mixer. ...
... This feature has been employed to obtain ultra-wideband detection with more than 40 dB of dynamic range and a detection responsivity of 33 V/W at 110 GHz [10]. It has also been reported that a power detector using a single GFET device can demodulate up to 4-Gb/s OOK signals at 96 GHz [9]. Compared with other technologies, a power detector using common-source MOS transistor provides limited dynamic range. ...
We demonstrate a full-fledged millimeter-wave graphene-based six-port receiver frontend at 90 GHz employing graphene power detectors. Exploiting the high responsivity and wide dynamic range reported for the state-of-the-art graphene field-effect transistors (GFETs), graphene power detectors are demonstrated beyond the maximum oscillation frequency, fmax, of the graphene transistor. The proposed circuit is fabricated on thinned SiC substrate and its functionality is verified by demodulation of 10-Mbps ON-OFF keying (OOK) digitally modulated signal.
... This technique is used in transmitters to control the output power levels of the power amplifier (PA) and in receivers to indicate the RF signal strength in order to adjust the gain of the receiver to ensure a constant signal strength at the input of the analog-to-digital converter (ADC). Employing GFETs as linear power detector devices has been reported in [10]- [12]. The demonstrated GFET power detectors are leveraging the nonlinear channel resistance property above the FET extrinsic f T and f max limitations. ...
... In addition, the substrate plays a key role in the achievable sensitivity. Detectors fabricated on expensive millimeter-wave 100 µm SiC with relative permittivity ( r ) equals 9 in [10] and [12] provide higher sensitivity compared to the work in [11] which was fabricated on 500 µm glass substrate with r equals 4, due to higher losses at high frequencies for microstrip transmission line-based design. ...
In this paper, we report the design, fabrication, and demonstration of a compact, V-band, zero-bias, and linear-in-dB power detector based on our in-house metal-insulator-graphene diode fabricated on a glass substrate. The presented circuit is optimized for the frequency band of 40-75 GHz. The measured prototype shows a repeatable measured dynamic range of at least 50 dB with down to -50 dBm sensitivity on 500-μm-thick quartz substrate. It also shows input return loss better than -9.5 dB over the entire design bandwidth. The measured tangential responsivity for the fabricated circuit on glass is 168 V/W at 2.5 GHz and 15 V/W at 60 GHz. The obtained results together with the robust device fabrication based on chemical vapor deposition graphene promote the proposed scheme and device for repeatable, statistically stable millimeter-wave, and submillimeter-wave applications.
... Many applications such as radio-frequency identification RF ID, automatic gain control AGC, energy harvesting and many other applications require sensitive, low-voltage drop, low capacitance power detectors. Employing Graphene FET's as power detector devices has been reported in [8]- [10]. The demonstrated FET-based power detectors are leveraging the non-linear channel resistance property above the FET extrinsic f T and f max limitations. ...
... In addition, the reported sensitivity is directly related to the used substrate. Detectors presented in [8] and [10] are fabricated on millimeter-wave SiC substrate with higher sensitivity compared to the work in [9] which is fabricated on glass which has higher substrate loss at higher frequencies. ...
... This FET has a mobility higher than 3000 cm 2 V −1 ·s, a gate length of 200 nm, f max =40 GHz, and a cutoff frequency of 50 GHz. A zero bias power detector T-gate FET working at 96 GHz with a gate length of 250 nm was also demonstrated using bilayer graphene with H intercalation as the channel [27]. The fabrication process was very similar to that reported in [24], with the T-gate having a drain-source distance of 1250 μm. ...
... For further details regarding the growth of scalable 2D materials other than graphene, the review paper [56] is recommended. Despite efforts spent to grow other 2D materials via CVD, graphene CVD growth technology is the most advanced method for growing monolayer and bilayer flakes on Cu [57] or directly on dielectric substrates [27]. ...
This article reviews the main physical properties of atomically thin semiconductors and the electronic devices based on them. We start with graphene, describing its physical properties and growth methods, followed by a discussion of its electronic device applications. Then, transition metal dichalcogenides (TMDs) are analyzed as a prototype of atomically thin semiconductors, their physical properties, growth methods, and electronic devices are discussed in detail. Finally, non-layered semiconducting membranes with thicknesses ranging from a few nanometers to about 50 nm, and considered as counterparts of atomically thin semiconductors, are analyzed, and their applications presented.
... However, the G-FETs have extrinsic f T and f Max of 38 GHz and 27 GHz respectively which is mainly limited by poor saturation behaviour in the output characteristics. For applications such as resistive mixers and power detectors [12] where V ds = 0, the 3-dB RF bandwidth, f 3−dB , can be estimated 1531-1309 © 2017 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. ...
... A FET can be used in different topologies for the realization of a FET based frequency mixer [12]. The difference in topology comes from the bias conditions and terminal (gate, drain or source) at which the signals are applied and extracted. ...
This letter presents the design, fabrication and characterization of the first graphene based monolithic microwave integrated circuit (MMIC) in microstrip technology operating in W-band. The circuit is a resistive mixer in a 250 nm graphene field effect transistor (G-FET) technology on a SiC substrate. A conversion loss of 18 dB is achieved which is limited by the available local oscillator (LO) power. The mixer exhibits a flat response over radio frequency (RF) range of 90-100 GHz. The RF bandwidth is also limited by the measurement setup.
... Research on 2D materials has garnered significant interest over the past two decades, with graphene emerging as the most promising candidate for high-frequency applications [1], primarily due to its exceptional carrier mobility [2,3]. Some examples of the main advancements can be found among radio-frequency (RF) power detection applications [4,5], antenna arrays [6], phase shifters [7], frequency multipliers [8][9][10], low noise amplifiers [11,12], modulators [13] and even THz absorbers [14,15]. Furthermore, the ambipolar electrical response of GFETs, i.e. their symmetric V-shaped transfer characteristics ( I DS versus V GS ) around the point of minimum conductivity, namely, the Dirac voltage ( V Dirac ), enables the exploration of new functionalities as well as the redesign and simplification of conventional RF circuits [16,17]. ...
Ambipolar conductance in graphene field-effect transistors (GFETs), and in particular their quasi-quadratic I–V transfer characteristic, makes these devices excellent candidates for exploiting subharmonic mixing at high frequencies. Several realizations have already demonstrated the ability of GFETs to compete with, or even improve, state-of-the-art mixers based on traditional technologies. Nonetheless, a systematic analysis of the influence on performance of both circuit design and technological aspects has not been conducted yet. In this work, we present a comprehensive assessment of the conversion losses by means of applying radio-frequency circuit design techniques in terms of filtering and matching, along with the impact stemming from physical and geometric variations of a fabricated graphene technology.
... Due to its high electrical and thermal conductivity, combined with thermal stability, mechanical strength, and chemical inertness, graphene has been considered for use in a variety of applications such as transistors [1,2], power detectors [3], mixers [4], lownoise amplifiers [5], frequency doublers [6], resonators [7], and sensors [8]. In addition, its relatively high transparency in the visible spectral range underlines its potential as a transparent electrode for optoelectronic devices, including light-emitting diodes and solar cells [9]. ...
Despite the impressive performance and incredible promise for a variety of applications, the wide-scale commercialization of graphene is still behind its full potential. One of the main challenges is related to preserving graphene’s unique properties upon transfer onto practically desirable substrates. In this work, few-layer graphene sheets deposited via liquid-phase transfer from copper onto a quartz substrate have been studied using a suite of experimental techniques, including scanning electron microscopy (SEM), Raman spectroscopy, admittance spectroscopy, and four-point probe electrical measurements. SEM measurements suggest that the transfer of graphene from copper foil to quartz using the aqueous solution of ammonium persulfate was accompanied by unintentional etching of the entire surface of the quartz substrate and, as a result, the formation of microscopic facet structures covering the etched surface of the substrate. As revealed by Raman spectroscopy and the electrical measurements, the transfer process involving the etching of the copper foil in a 0.1 M solution of (NH4)2S2O8 resulted in its p-type doping. This was accompanied by the appearance of an electronic gap of 0.022 eV, as evidenced by the Arrhenius analysis. The observed increase in the conductance of the samples with temperature can be explained by thermally activated carrier transport, dominating the scattering processes.
... Although further improvement of the RF device performance is expected [15], the already proven GFET figures of merit (FoMs) allow the design of applications operating at millimeter wave (mmWave) frequencies. Those encompass applications where the GFET leverages either its remarkable high transconductance, e.g., low noise amplifiers (LNAs) [16]; or the graphene ambipolarity such as resistive mixers [17][18][19][20][21]; frequency multipliers [21,22]; and power detectors [23], all of them demonstrated to properly operate in the gigahertz band. ...
The Dirac voltage of a graphene field-effect transistor (GFET) stands for the gate bias that sets the charge neutrality condition in the channel, thus resulting in a minimum conductivity. Controlling its dependence on the terminal biases is crucial for the design and optimization of radio-frequency applications based on multiple GFETs. However, the previous analysis of such dependence carried out for single devices is uncomplete and if not properly understood could result in circuit designs with poor performance. The control of the Dirac point shift (DPS) is particularly important for the deployment of graphene-based differential circuit topologies where keeping a strict symmetry between the electrically balanced branches is essential for exploiting the advantages of such topologies. This note sheds light on the impact of terminal biases on the DPS in a real device and sets a rigorous methodology to control it so to eventually optimize and exploit the performance of radio-frequency applications based on GFETs.
... With the growing interest in epitaxial Chemical Vapor Deposition (CVD) of graphene on semiinsulating (SI) silicon carbide and noticeable progress in applied activities [1][2][3][4][5][6], it has become crucial to reliably quantify, compare and categorize graphene's properties. ...
In this report we demonstrate a method for direct determination of the number of layers of hydrogen-intercalated quasi-free-standing epitaxial Chemical Vapor Deposition graphene on semiinsulating vanadium-compensated on-axis 6H-SiC(0001). The method anticipates that the intensity of the substrate’s Raman-active longitudinal optical A1 mode at 964 cm^(−1) is attenuated by 2.3 % each time the light passes through a single graphene layer. Normalized to its value in a graphene-free region, the A1 mode relative intensity provides a greatly enhanced topographic image of graphene and points out to the number of its layers within the terraces and step edges, making the technique a reliable diagnostic tool for applied research.
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... The technology of graphene epitaxy through Chemical Vapor Deposition (CVD) from decomposed propane [1] on semiinsulating (SI) on-axis SiC(0001) has already been verified in a number of potential applications, including broad-temperature magnetic field sensing [2,3] and monolithic microwave integrated circuits (MMICs) [4][5][6]. Historically, first to synthesize on SiC was n-type monolayer graphene in the form of a covalently bonded to the substrate carbon buffer layer [7][8][9][10] topped with a single graphene layer. The technology's potential was further improved with the introduction of hydrogen atom intercalation [11][12][13][14][15][16] that converts the electrically inactive buffer [10] into quasi-free-standing (QFS) monolayer graphene [17] and monolayer graphene into QFS-bilayer graphene [11,18]. ...
In this report we investigate structural and electrical properties of epitaxial Chemical Vapor Deposition quasi-free-standing graphene on an unintentionally-doped homoepitaxial layer grown on a conducting 4H-SiC substrate 4° off-axis from the basal [0001] direction towards [11-20]. Due to high density of SiC vicinal surfaces the deposited graphene is densely stepped and gains unique characteristics. Its morphology is studied with atomic force and scanning electron microscopy. Its few-layer character and p-type conductance are deduced from a Raman map and its layers structure determined from a high-resolution X-ray diffraction pattern. Transport properties of the graphene are estimated through Hall effect measurements between 100 and 350 K. The results reveal an unusually low sheet resistance below 100 Ω/sq and high hole concentration of the order of 10¹⁵ cm⁻². We find that the material’s electrical properties resemble those of an epitaxially-grown SiC PIN diode, making it an attractive platform for the semiconductor devices technology.
https://authors.elsevier.com/a/1cvqR5aLOStCsP
... Graphene is a two-dimensional (2D) planar structure built up by carbon atoms in a honeycomb lattice, which possesses many unique chemical, thermal, electronic, and optical characteristics [7][8][9]. In particular, the surface conductivity can be dynamically altered over a wide range by changing bias voltage, which makes it a promising candidate for THz and infrared frequency bands, such as antennas [6,10,11], polarizers [12], phase shifters [13], switches [14], some THz modulators [15], demodulators [16], mixers [17], and THz receivers [18]. In References [10,11], graphene works as a radiation part of the antennas because of the capability of transmitting the surface plasmon polariton (SPP) waves. ...
In this letter, a novel 3D multi-beam reconfigurable THz loop antenna capable of steering its main beam in the semi-sphere space (θ ϵ {0°, ±5°, ±10°}; φ ϵ {0°, 30°, 60°, 90°, 120°, 150°}) is presented. The antenna is based on a switchable circular high impedance surface (HIS) using the graphene–metal hybrid approach. The effect of gate voltage on the conductivity of graphene and the switchable reflection characteristic of the graphene-based HIS are combined in the design. Changing the chemical potential of different graphene-based HIS units can effectively adjust the beam direction. The performance of the antenna is analyzed through its reflection coefficients and gain radiation patterns, and simulated results show that the maximum gain can reach 3.23 dBi at 0.5 THz.
... Epitaxial CVD graphene on semiinsulating (SI) silicon carbide has already been verified as a likely material for the future graphene applications. Reported monolithic microwave integrated circuits (MMICs) [13]- [15] show its promise in millimeter-wave electronics. They take advantage of graphene's charge carriers mobility. ...
In this report, we demonstrate a novel high-temperature Hall effect sensor that is based on quasi-free-standing monolayer graphene epitaxially grown on high-purity semiinsulating (SI) on-axis 4H-SiC(0001) substrate in a chemical vapor deposition process. To ensure statistical perspective, characteristics of 23 elements are determined as a function of temperature ranging from 300 to 770 K. Passivated with a 100-nm-thick atomic-layer-deposited aluminum oxide, the sensor offers current-mode sensitivity of 80 V/AT with thermal stability of -0.02%/K within the range between 300 and 573 K, and -0.06%/K between 573 and 770 K. The sensor's room-temperature output voltage is monitored in the magnetic field from -300 to +300 mT and its offset voltage at 0 T is assessed. Its high-temperature electrical properties are explained through a double-carrier transport involving spontaneous-polarization-induced holes in the graphene layer and thermally activated electrons emitted from a deep acceptor level related to silicon vacancy VSi^1-/2- occupying the k site of the 4H-SiC lattice. The sensor is compared with a previously reported one on vanadium-compensated SI on-axis 6H-SiC(0001). The new sensor's applicability to magnetic field detection at high temperatures is verified.
... Recently, many graphene-based microwave circuits have been reported employing graphene field effect transistors (GFETs). This includes frequency mixers, power detectors, and amplifiers [2]- [5]. Among them, GFET-based mixers attracted great interest as a crucial building block for the anticipated graphene-based communication systems. ...
In this paper we present the design, fabrication and characterisation of a fully-integrated, wideband double-balanced mixer based on graphene diodes. The circuit is implemented on glass substrate utilising an in-house monolithic microwave integrated circuits (MMIC) process and provides 10 dB conversion loss at 10 GHz with a 3-dB bandwidth of 6 GHz. The measured LO-to-RF isolation is better than 25 dB in the entire band with better than 12 dB return loss at both LO and RF ports in 50 Ω measurement system. To the best knowledge of the authors, the mixer conversion-loss performance outperforms the state-of-the-art graphene-transistor-based mixer circuits.
... Los estudios obtenidos en (Habibpour, et al., 2016) analizan la demodulación de una señal de encendido y apagado multi-Gb/s a través de un portador a 96 GHz utilizando un transistor FET de grafeno a una escala de 250 nm como detector de potencia con polarización a cero, demostrando así el potencial que tienen este tipo de dispositivos y los niveles de comunicación que pueden obtenerse a dichas frecuencias. De igual forma ocurre en (Mao, et al., 2016(Mao, et al., ) y (W., et al., 2017 con la implementación de grafeno para lograr osciladores GTFET (túnel de grafeno FET) en donde se analizan parámetros clave para el dispositivo tales como la frecuencia, la potencia de salida, funcionamiento, oscilación máxima, potencia máxima, relación entre frecuencia y potencia y rendimiento, y todo encaminado a lograr una comunicación eficaz. ...
En los últimos años, la nanotecnología ha marcado un hito en la evolución de las comunicaciones, lo que ha permitido el desarrollo de nuevas aplicaciones y la estandarización de nuevos materiales en una escala nanométrica llamada nanomateriales. Algunos de ellos son el grafeno y sus derivados como los nanotubos de carbono y algunos compuestos como los metamateriales cuyas propiedades y características de tipo electrónico y físico son totalmente compatibles, permitiendo una fusión fácil con las telecomunicaciones. Y es precisamente lo que se pretende mediante este artículo; proporcionar una perspectiva desde la academia para identificar algunos tipos de nanomateriales que nos planteamos algunas preguntas como ¿qué tipo de materiales son?, ¿qué propiedades tienen?, ¿qué clasificación poseen?, ¿cuáles son algunas de las aplicaciones más importantes en el campo de las telecomunicaciones?, y ¿qué desarrollos y aplicaciones hay actualmente? Así, entramos explorando las nanocomunicaciones.
... the intrinsic nonlinearity provided by GFETs. This includes frequency multipliers 4 , power detectors up to THz frequencies 5,6 , and mixers [7][8][9][10] , which are demonstrated at frequencies up to 200 GHz 11 . On the contrary, few amplifiers have been reported either with moderate power gain of 7 dB up to 4 GHz 12 , or with higher gain at lower frequency; 10 dB at 1 GHz 13 . ...
This work demonstrates a design approach which enables the fabrication of fully integrated radio frequency (RF) and millimetre-wave frequency, direct-conversion graphene receivers by adapting the frontend architecture to exploit the state-of-the-art performance of recently reported waferscale CVD metal-insulator-graphene (MIG) diodes. As a proof-of-concept, we built a fully integrated microwave receiver in the frequency range 2:12:7 GHz employing the strong nonlinearity and the high responsivity of MIG diodes to successfully receive and demodulate complex, digitally modulated communication signals at 2:45 GHz. In addition, the fabricated receiver uses zero biased MIG diodes and consumes zero dc power. With the flexibility to be fabricated on different substrates, the prototype receiver frontend is fabricated on a low-cost, glass substrate utilising a custom-developed MMIC process backend which enables high performance passive components. The measured performance of the prototype makes it suitable for Internet-of-Things (IoT), Radio Frequency Identification (RFID) systems for medical and communications applications.
... Besides many applications in the Radio-Frequency (RF) domain [20,21,22], graphene has shown unique potential for the development of plasmonic waveguides and antennas operating in the terahertz band. In the following, we review the state-of-the-art in this thriving field. ...
Graphene is a unique material for the implementation of terahertz antennas due to extraordinary properties of the resulting devices, such as tunability and compactness. Existing graphene antennas are based on pure plasmonic structures, which are compact but show moderate to high losses. To achieve higher efficiency with low cost, one can apply the theory behind dielectric resonator antennas widely used in millimeter-wave systems. This paper presents the concept of hybridization of surface plasmon and dielectric wave modes. Then, via an analysis of one-dimensional structures, a comparison of the potential capabilities of pure and hybrid plasmonic antennas is performed from the perspectives of radiation efficiency, tunability, and miniaturization. Additionally, the impact of the quality of graphene upon the performance of the compared structures is evaluated. On the one hand, results show that hybrid structures deliver high gain with moderate miniaturization and tunability, rendering them suitable for applications requiring a delicate balance between the three aspects. On the other hand, pure plasmonic structures can provide higher miniaturization and tunability, yet with low efficiency, suggesting their use for application domains with high flexibility requirements or stringent physical constraints.
... G-FETs with intrinsic current-gain cutoff frequencies (f T ) of 400 GHz and maximum oscillation frequency (f MAX ) of 100 GHz have been demonstrated 3,4 . In addition, many G-FET based circuits including frequency multipliers [5][6][7][8] , mixers 6,[9][10][11][12] , amplifiers [13][14][15][16] and power detectors [17][18][19][20] have been presented. Most of the demonstrated circuits so far are not integrated circuits (ICs) requiring external circuitries for operation. ...
In recent years, the demand for high data rate wireless communications has increased dramatically, which requires larger bandwidth to sustain multi-user accessibility and quality of services. This can be achieved at millimeter wave frequencies. Graphene is a promising material for the development of millimeter-wave electronics because of its outstanding electron transport properties. Up to now, due to the lack of high quality material and process technology, the operating frequency of demonstrated circuits has been far below the potential of graphene. Here, we present monolithic integrated circuits based on epitaxial graphene operating at unprecedented high frequencies (80–100 GHz). The demonstrated circuits are capable of encoding/decoding of multi-gigabit-per-second information into/from the amplitude or phase of the carrier signal. The developed fabrication process is scalable to large wafer sizes.
In this report, we present transfer-free p-type hydrogen-intercalated quasi-free-standing epitaxial Chemical
Vapor Deposition graphene on 15-mm × 15-mm semi-insulating vanadium-compensated on-axis 6H–SiC(0001),
characterized in that its room-temperature direct-current Hall-effect-derived hole mobility 𝜇p = 5019 cm2/Vs,
and its statistical number of layers (N), as indicated by the relative intensity of the SiC-related Raman-active
longitudinal optical A1 mode at 964 cm−1, equals N = 1.05. The distribution of the ellipsometric angle 𝛹
measured at an angle of incidence of 50◦ and 𝜆 = 490 nm points out to N = 0.97. The close-to-unity value of
N implies that the material under study is a close-to-perfect quasi-free-standing monolayer, which is further
confirmed by High-Resolution Transmission Electron Microscopy. Therefore, its spectroscopic properties, which
include the Si–H peak at 2131 cm−1, the histograms of 𝛹 and 𝛥, and the Raman G and 2D band positions,
widths, and the 2D-to-G band intensity ratios, constitute a valuable reference for this class of materials.
Graphene field-effect transistors (GFETs) exhibit negligible transconductance under two scenarios: for any gate-to-source voltage when the drain-to-source voltage is set to zero and for an arbitrary drain-to-source voltage provided that the gate-to-source voltage equals the Dirac voltage. Hence, extracting the channel and the parasitic series resistances from
S
-parameters under these conditions enables analyzing their dependence on the gate and drain biases. This is fundamental to assess the portion of the output resistance that is controlled by the gate. Besides, the drain bias dependence of the drain and source resistances is also evidenced. Within the proposal, resistive components accounting for the lossy nature of the gate capacitance are incorporated into the model, which exhibits a broadband correlation with experimental data. This avoids the series resistances to be considered as frequency dependent in the model.
Exploiting ambipolar electrical conductivity based on graphene field‐effect transistors has raised enormous interest for high‐frequency (HF) analog electronics. Controlling the device polarity, by biasing the graphene transistor around the vertex of the V‐shaped transfer curve, enables to redesign and highly simplify conventional analog circuits, and simultaneously to seek for multifunctionalities, especially in the HF domain. This study presents new insights for the design of different HF applications such as power amplifiers, mixers, frequency multipliers, phase shifters, and modulators that specifically leverage the inherent ambipolarity of graphene‐based transistors.
This article presents a 39-GHz 800-Mb/s antenna-coupled on–off-key (OOK) receiver with a baseband output capable of driving a 50-
load. The antenna-coupled receiver demonstrates a bit error rate (BER) of 10
over a range of 18 cm while dissipating only 0.71 mW for a record energy efficiency per distance metric of 0.049 pJ/bit/cm. A wireline version of the receiver achieves a record sensitivity level of
36 dBm without preamplification while dissipating only 1.15 mW, resulting in an energy efficiency of 1.44 pJ/bit at a BER of 10
. Including 11.5 dB of RF gain prior to the wireline receiver, 800-Mb/s communication is demonstrated at 3.67 m for a BER of 10
. The low power consumption and long range make this receiver suitable for scaling to hundreds or thousands of elements in massive multi-in–multi-output (MIMO) arrays for next-generation millimeter-wave wireless communications systems.
In this report, we introduce a novel method based on low-frequency noise analysis for the assessment of quality and pattern of inhomogeneity in intentionally-aged Hall effect sensors featuring hydrogen-intercalated quasi-free-standing epitaxial Chemical Vapor Deposition graphene mesa on semi-insulating high-purity on-axis 4H-SiC(0001), all passivated with a 100-nm-thick atomic-layer-deposited Al2O3 layer. Inferring from the comparison of the measured noise and one calculated for a homogeneous sensor, we hypothesize about possible unintentional contamination of the sensors’ active regions. Following in-depth structural characterization based on Nomarski interference contrast optical imaging, confocal micro-Raman spectroscopy, high-resolution Transmission Electron Microscopy and Secondary Ion Mass Spectrometry, we find out that the graphene’s quasi-free-standing character and p-type conductance make the Al2O3/graphene interface exceptionally vulnerable to uncontrolled contamination and its unrestrained lateral migration throughout the entire graphene mesa, eventually leading to the blistering of Al2O3. Thus, we prove the method’s suitability for the detection of these contaminants’ presence and location, and infer on its applicability to the investigation of any contamination-induced inhomogeneity in two-dimensional systems. https://authors.elsevier.com/a/1eyP64xMlkIhhc
We demonstrate the design, fabrication, and characterization of wafer-scale, zero-bias power detectors based on two-dimensional MoS2 field effect transistors (FETs). The MoS2 FETs are fabricated using a wafer-scale process on 8 μm thick Polyimide film, which in principle serves as flexible substrate. The performances of two CVD-MoS2 sheets, grown with different processes and showing different thicknesses, are analyzed and compared from the single device fabrication and characterization steps to the circuit level. The power detector prototypes exploit the nonlinearity of the transistors above the cut-off frequency of the devices. The proposed detectors are designed employing a transistor model based on measurement results. The fabricated circuits operate in Ku-band between 12 and 18 GHz, with a demonstrated voltage responsivity of 45 V/W at 18 GHz in the case of monolayer MoS2 and 104 V/W at 16 GHz in the case of multilayer MoS2 , both achieved without applied DC bias. They are the best performing power detectors fabricated on flexible substrate reported to date. The measured dynamic range exceeds 30 dB outperforming other semiconductor technologies like silicon complementary metal oxide semiconductor (CMOS) circuits and GaAs Schottky diodes. This article is protected by copyright. All rights reserved.
Over the past two decades, the research on two-dimensional materials has received much interest. Graphene is the most promising candidate regarding high frequency applications thus far due to is high carrier mobility. This review discusses the research about the employment of graphene in micro- and millimetre-wave circuits. The review starts with the different methodologies to grow and transfer graphene before discussing the way graphene-based field-effect-transistors (GFETs) and diodes are built. A review on different approaches for realising these devices is provided before discussing the employment of both GFETs and graphene diodes in different micro- and millimetre-wave circuits, showing the possibilities but also the limitations of this 2D-material for high frequency applications.
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The interest in graphene-based electronics is due to graphene’s great carrier mobility, atomic thickness, resistance to radiation, and tolerance to extreme temperatures. These characteristics enable the development of extremely miniaturized high-performing electronic devices for next-generation radiofrequency (RF) communication systems. The main building block of graphene-based electronics is the graphene-field effect transistor (GFET). An important issue hindering the diffusion of GFET-based circuits on a commercial level is the repeatability of the fabrication process, which affects the uncertainty of both the device geometry and the graphene quality. Concerning the GFET geometrical parameters, it is well known that the channel length is the main factor that determines the high-frequency limitations of a field-effect transistor, and is therefore the parameter that should be better controlled during the fabrication. Nevertheless, other parameters are affected by a fabrication-related tolerance; to understand to which extent an increase of the accuracy of the GFET layout patterning process steps can improve the performance uniformity, their impact on the GFET performance variability should be considered and compared to that of the channel length. In this work, we assess the impact of the fabrication-related tolerances of GFET-base amplifier geometrical parameters on the RF performance, in terms of the amplifier transit frequency and maximum oscillation frequency, by using a design-of-experiments approach.
Electronic devices that operate at terahertz frequencies will require new materials that exhibit higher carrier velocities than traditional semiconductors. Calculations show that cadmium arsenide, a 3D topological (Dirac) semimetal, is an excellent candidate for field effect transistors that operate at frequencies above 1 THz. Moreover, such transistors have unique advantages that are enabled by the properties of Dirac electrons. These include predictions of an unprecedented linearity of the transconductance and cutoff frequencies over a large operating range and cutoff frequencies that remain above 1 THz at carrier densities as low as 1011 cm−2. The calculations are underpinned by measurements of devices with cadmium arsenide channels. Extremely low contact resistances (<2 × 10−9 Ω cm2), high electron velocities (>7 × 105 m s−1), and unprecedentedly large current densities (up to 10 A mm−1) are demonstrated. Current modulation (>50%) and transconductance already achieved in the early transistors show the potential for large (>10 ×) improvements by reducing interface trap densities. The results demonstrate the significant potential of topological semimetals for high‐speed transistors operating in the THz regime and open up new opportunities for next‐generation RF circuits. Electronic devices that operate at terahertz frequencies will require new materials that exhibit higher carrier velocities than traditional semiconductors. Here, it is shown that cadmium arsenide, a 3D topological (Dirac) semimetal, is an excellent candidate for field effect transistors that operate at frequencies above 1 THz.
This paper presents a wideband, zero-biased power detector circuit based on metal-insulator-Graphene (MIG) diodes fabricated on quartz substrate. The wideband performance, outstanding tangential signal sensitivity (TSS) and dynamic range (DR) of the proposed detector are obtained by employing the diode's strong nonlinearity together with an artificial transmission line architecture. S11S11 better than −13 dB up to at least 70 GHz due to measurement equipment limitations is demonstrated. Measurements show a DR of at least 60 dB with TSS better than −65dBm at 70 GHz. Responsivity measurements for the fabricated detector are 148 mV/mW at 2.5 GHz and 87 mV/mW at 70 GHz. Chip area of the fabricated prototype is 0.15 mm2 including pads. A proposed figure-of-merit is used to determine the optimum number of stages quantitatively. According to the best knowledge of the authors, the proposed power detector has the lowest TSS and the widest DR for grauhene-based detectors.
For nearly half a century, the microelectronics industry has flourished based on the scaling of the silicon CMOS transistor technology. However, the race to transistor miniaturization encounters inevitable physical barriers. Thus, many technological works are under way for the realization of future transistors on emerging and advanced technologies. These technologies, notably the graphene and the CMOS FD-SOI, represent great opportunities for research in the fields of microelectronics, and especially for the design of radiofrequency and millimeter circuits. Besides, with the rising evolution of wireless devices and services, researchers are intensively working on the fifth generation (5G) wireless systems. The demand for high speed data and the need for more spectrum, have motivated the use of millimeter wave carrier frequencies. Therefore, the 5G research is faced with an evolving set of challenges. One of the major challenges of the next generation communication technology is reducing energy consumption. In fact, the power efficiency is directly related to the reliability and cost of the communication systems. It is widely known that the radiofrequency power amplifier is the most power consuming component in the radio transceivers, and is also one of the most critical building blocks in radio front-end. Therefore, research in this area is crucial for next generation communication systems. Consequently, the objective of this thesis is to study and design power amplifiers on emerging and advanced technologies for 5G applications.
Benefit from exceptional electrical transport properties, graphene receives worldwide attentions, especially in the domain of high frequency electronics. Due to absence of effective bandgap causing off-state the device, graphene material is extraordinarily suitable for analog circuits rather than digital applications. With this unique ambipolar behavior, graphene can be exploited and utilized to achieve high performance for frequency multipliers. Here, dual-gated graphene field-effect transistors have been firstly used to achieve frequency quadrupling. Two Dirac points in the transfer curves of the designed GFETs can be observed by tuning top-gate voltages, which is essential to generate the fourth harmonic. By applying 200 kHz sinusoid input, arround 50% of the output signal radio frequency power is concentrated at the desired frequency of 800 kHz. Additionally, in suitable operation areas, our devices can work as high performance frequency doublers and frequency triplers. Considered both simple device structure and potential superhigh carrier mobility of graphene material, graphene-based frequency quadruplers may have lots of superiorities in regards to ultrahigh frequency electronic applications in near future. Moreover, versatility of carbon material system is far-reaching for realization of complementary metal-oxide-semiconductor compatible electrically active devices.
A 200-GHz integrated resistive subharmonic mixer based on a single chemical vapor deposition graphene field-effect transistor (G-FET) is demonstrated experimentally. This device has a gate length of 0.5 μm and a gate width of 2x40 μm. The G-FET channel is patterned into an array of bow-tie-shaped nanoconstrictions, resulting in the device impedance levels of ~50 Ω and the ON-OFF ratios of ≥4. The integrated mixer circuit is implemented in coplanar waveguide technology and realized on a 100-μm-thick highly resistive silicon substrate. The mixer conversion loss is measured to be 29 ± 2 dB across the 185-210-GHz band with 12.5-11.5 dBm of local oscillator (LO) pump power and >15-dB LO-RF isolation. The estimated 3-dB IF bandwidth is 15 GHz.
This paper presents a high-efficiency 60-GHz on-off keying (OOK) demodulator for high-speed short-range wireless communications such as wireless network-on-chip (WiNoC) applications. Targeting at data rates of beyond 16 Gb/s, the OOK demodulator consists of a wideband envelope detector (ED) and a single-stage baseband (BB) peaking amplifier. Novel dual gain-boosting techniques improve the gain, bandwidth, and out-of-band rejection of the ED. In addition, an actively-enhanced tunable inductor (AETI) load in the BB amplifier not only significantly reduces its area overhead, but also provides a tunable peaking level. Fabricated in a 65-nm bulk CMOS process, the OOK demodulator consumes only 4.6 mW from a 1-V supply, and occupies an active area of 0.043 . A maximum data rate of 18.7 Gb/s with a bit-error rate less than is demonstrated through measurements, which translates to a bit-energy efficiency of 0.25 pJ/bit.
A 30-GHz integrated subharmonic mixer based on a single graphene field-effect transistor (G-FET) has been designed, fabricated, and characterized. The mixer is realized in microstrip technology on a 250-m-high-resistivity silicon substrate. In order to enhance the current on–off ratio, the G-FET utilizes a channel consisting of an array of bow-tie structured graphene, yielding a current on–off ratio of 7. A conversion loss (CL) of 19 1 dB over the frequency range of 24–31 GHz is obtained with a local oscil-lator (LO) to RF isolation better than 20 dB at an LO power of 10 dBm. The overall minimum CL is 18 dB at 27 GHz. The mixer has a 3 GHz 1-dB IF bandwidth, which is achieved with a fixed LO signal of 15 GHz. The mixer linearity is characterized and the highest third-order intercept point is measured to be 12.8 dBm. Index Terms—Graphene, harmonic-balance analysis, microwave field-effect transistors (FETs), millimeter-wave mixers, monolithic microwave integrated circuit (MMIC), subharmonic resistive mixers.
We report on the first complete RF characterization of graphene field-effect transistor subharmonic resistive mixers in the frequency interval 2–5 GHz. The analysis includes conversion loss (CL), noise figure (NF), and intermodulation distortion. Due to an 8-nm thin Al2O3 gate dielectric, the devices operate at only 0 dBm of local oscillator (LO) power with an optimum measured CL in the range of 20–22 dB. The NF closely mimics the CL, thus determining the noise to be essentially thermal in origin, which is promising for cryogenic applications. The highest input third-order intercept point is measured to be 4.9 dBm at an LO power of 2 dBm.
A direct conversion demodulator at 60GHz based on Gilbert cells down-converter is presented in this paper. The OOK modulation allows using a single detector on receiver side to discriminate the 0 or 1 data. The conventional diode based detector presents conversion losses and obviously a high noise figure. Derived from the classic Gilbert cell mixer the demodulator presents a conversion gain of 9.7dB, a Noise Figure of 10dB for an input signal as low as −28dBm. This high sensitivity allows applications as chip to chip communications with high data rate. A data rate of 10Gbps has been measured without significant degradation with an efficiency of 2.1pJ/bit.
The unique optoelectronic properties of graphene make it an ideal platform for a variety of photonic applications, including fast photodetectors, transparent electrodes in displays and photovoltaic modules, optical modulators, plasmonic devices, microcavities, and ultra-fast lasers. Owing to its high carrier mobility, gapless spectrum and frequency-independent absorption, graphene is a very promising material for the development of detectors and modulators operating in the terahertz region of the electromagnetic spectrum (wavelengths in the hundreds of micrometres), still severely lacking in terms of solid-state devices. Here we demonstrate terahertz detectors based on antenna-coupled graphene field-effect transistors. These exploit the nonlinear response to the oscillating radiation field at the gate electrode, with contributions of thermoelectric and photoconductive origin. We demonstrate room temperature operation at 0.3 THz, showing that our devices can already be used in realistic settings, enabling large-area, fast imaging of macroscopic samples.
A wafer-scale graphene circuit was demonstrated in which all circuit components, including graphene field-effect transistor
and inductors, were monolithically integrated on a single silicon carbide wafer. The integrated circuit operates as a broadband
radio-frequency mixer at frequencies up to 10 gigahertz. These graphene circuits exhibit outstanding thermal stability with
little reduction in performance (less than 1 decibel) between 300 and 400 kelvin. These results open up possibilities of achieving
practical graphene technology with more complex functionality and performance.
Here we discuss on detection using antenna-coupled field effect transistors. We show, that gate-to-channel separation plays strong role for the dispersion of plasmons excited within the channel changing from gated 2D to ungated 2D plasmon. This change also strongly affects the impedance and the efficiency of rectification. We present experimental data which clearly indicates on with plasmonic rectification competing physical phenomenon. There are strong indications, that this additional signal originates from the inhomogeneous heating of charge carriers i.e., diffusion of “warm” electrons.
We report the first experimental results of single graphene-on-glass FET-based envelope detectors operating at digital communication data rate of 20 Mb/s with RF carrier frequency above 5 GHz. The new ambipolar GFET envelope detectors operated with zero power consumption, which is potentially ideal for ultra-low-power wireless networks. GFET ambipolar envelope detectors offer excellent 40 dB linear dynamic range over the incoming RF power with sensitivity down to -60 dBm. For the first time, we demonstrated that the ambipolar nature of graphene FETs offer performance advantages over state-of-the-art CMOS FET-based envelope detector ICs for ultra-low-power wireless communications. With graphene's transferability to any substrate, further development of GFETs could potentially deliver higher data rates to ubiquitous ULP communication platforms.
We present terahertz (THz) detectors based on top-gated graphene field effect transistors (GFETs) with integrated split-bow-tie antennas. The GFETs were fabricated using graphene grown by chemical vapor deposition (CVD). The THz detectors are capable of room-temperature rectification of a 0.6 THz signal and achieve a maximum optical responsivity better than 14 V/W and minimum optical noise-equivalent power (NEP) of 515 pW/Hz^0.5. Our results are a significant improvement over previous work on graphene direct detectors and are comparable to other established direct detector technologies. This is the first time room-temperature direct detection has been demonstrated using CVD graphene, which introduces the potential for scalable, wafer-level production of graphene detectors.
This paper presents design and characterization of a 60-GHz On-Off Keying (OOK) demodulator for low-power ultra-high-speed wireless communications. The core of the demodulator consists of a fully-balanced envelope detector to improve the detection sensitivity compared to the conventional single-ended configuration. A feed-forward offset-compensation technique is utilized to eliminate the DC saturation in the limiting amplifier of the demodulator. Integrated in a 0.25-μm SiGe BiCMOS technology, the demodulator can operate with data rates from 4 Gbps to 11.5 Gbps with 10-12 BER over a 60-GHz carrier. The demodulator consumes 27.5 mW of DC power from a 1.6-V supply voltage, accounting for all bias circuits and a test output buffer. An energy efficiency of 2.4 pJ/bit is achieved at a data rate of 11.5 Gbps.
Reported is the realisation of a graphene FET microwave amplifier operating at 1 GHz, exhibiting a small-signal power gain of 10 dB and a noise figure of 6.4 dB. The amplifier utilises a matching inductor on the gate yielding a return loss of 20 dB. The design is optimised for maximum gain and the optimum noise figure is extracted by noise modelling and predicted to be close to 1 dB for the intrinsic graphene FET at this frequency. The presented results complement existing graphene FET applications and are promising for future graphene microwave circuits.
A 30-GHz integrated subharmonic mixer based on a single graphene field-effect transistor (G-FET) has been designed, fabricated, and characterized. The mixer is realized in microstrip technology on a 250- μm-high-resistivity silicon substrate. In order to enhance the current on-off ratio, the G-FET utilizes a channel consisting of an array of bow-tie structured graphene, yielding a current on-off ratio of 7. A conversion loss (CL) of 19 ± 1 dB over the frequency range of 24-31 GHz is obtained with a local oscillator (LO) to RF isolation better than 20 dB at an LO power of 10 dBm. The overall minimum CL is 18 dB at 27 GHz. The mixer has a 3 GHz ± 1-dB IF bandwidth, which is achieved with a fixed LO signal of 15 GHz. The mixer linearity is characterized and the highest third-order intercept point is measured to be 12.8 dBm.
Graphene has attracted much interest as a future channel material in radio frequency electronics because of its superior electrical properties. Fabrication of a graphene integrated circuit without significantly degrading transistor performance has proven to be challenging, posing one of the major bottlenecks to compete with existing technologies. Here we present a fabrication method fully preserving graphene transistor quality, demonstrated with the implementation of a high-performance three-stage graphene integrated circuit. The circuit operates as a radio frequency receiver performing signal amplification, filtering and downconversion mixing. All circuit components are integrated into 0.6 mm(2) area and fabricated on 200 mm silicon wafers, showing the unprecedented graphene circuit complexity and silicon complementary metal-oxide-semiconductor process compatibility. The demonstrated circuit performance allow us to use graphene integrated circuit to perform practical wireless communication functions, receiving and restoring digital text transmitted on a 4.3-GHz carrier signal.
We report direct radio-frequency (RF) and millimeter-wave detection of epitaxial graphene field-effect transistors (FETs) up to 110 GHz with no dc biases applied, leveraging the nonlinearity of the channel resistance. A linear dynamic range of >; 40 dB was measured, providing at least 20-dB greater linear dynamic range compared to conventional CMOS detectors at transistor level. The measured noise power of the graphene FETs was ~7.5 × 10-18 V2/Hz at zero bias and without 1/f noise. At a 50-Ω load, measured detection responsivity was 71 V/W at 2 GHz to 33 V/W at 110 GHz. The noise-equivalent power at 110 GHz was estimated to be ~80 pW/Hz0.5. For the first time, we demonstrated graphene FETs as zero-bias ultrawideband direct RF detectors with comparable or better performance than state-of-the-art FET-based detectors without dc biases applied.
The maximum oscillation frequency (fmax) quantifies the practical upper bound
for useful circuit operation. We report here an fmax of 70 GHz in transistors
using epitaxial graphene grown on the C-face of SiC. This is a significant
improvement over Si-face epitaxial graphene used in the prior high frequency
transistor studies, exemplifying the superior electronics potential of C-face
epitaxial graphene. Careful transistor design using a high {\kappa} dielectric
T-gate and self-aligned contacts, further contributed to the record-breaking
fmax.
Square-law power detection circuits with on-chip antennas and amplifiers are presented for the detection of 0.65-THz radiation
in a low-cost 0.25-μm CMOS technology. The circuit architecture combines metal-insulator-metal (MIM) coupling capacitors with NMOS transistors
to facilitate self-mixing in a resistive mixer. A low-frequency (quasi-static) and a high-frequency (non-quasi-static) analysis
of the broad-band circuit is presented. Current and voltage readout techniques of non-amplified detectors are compared, and
exhibit a measured responsivity of 5.3 mA/W and 150 V/W respectively. A monolithic integrated 3×5 pixel focal-plane array
has been used for single-pixel and multi-pixel imaging of concealed objects at 0.65 THz.
A 5 Gbit/s CMOS receiver for 60 GHz impulse radio is realised. It contains a fully differential envelope detector for differential inputs, a current mode offset canceller for robustness against PVT variations, and a high-speed comparator with hysteresis for noise immunity. The receiver is fabricated using a 90 nm CMOS process with a size of 950 750 m. The total power consumption of the receiver is 49 mW at 5 Gbit/s.
A focal-plane array (FPA) for room-temperature detection of 0.65-THz radiation has been fully integrated in a low-cost 0.25 mum CMOS process technology. The circuit architecture is based on the principle of distributed resistive self-mixing and facilitates broadband direct detection well beyond the cutoff frequency of the technology. The 3 timesZ 5 pixel array consists of differential on-chip patch antennas, NMOS direct detectors, and integrated 43-dB voltage amplifiers. At 0.65 THz the FPA achieves a responsivity ( Rv ) of 80 kV/W and a noise equivalent power (NEP) of 300 pW/ radic{Hz}. Active multi-pixel imaging of postal envelopes demonstrates the FPAs potential for future cost-effective terahertz imaging solutions.
This article provides an introduction to a panel session at the 2009 International Microwave Symposium (IMS 2009) on enabling multi-gigabit per second (Gb/s) wireless communication links. Blasting beams of high-speed data through free space is not new. Terahertz spectrum near visible light has been used for ultrahigh-speed optical links for many years. Newly released millimeter-wave (mm-wave) bands provide a similar potential but with different operating characteristics. Advances in manufacturing are yielding high-reliability, high-frequency mm-wave devices, faster digital field programmable gate arrays (FPGA) processors, and superfast analog-to-digital (A/D) and digital-to-analog (D/A) converters that enable higher frequency transceivers, faster modems, and more cost-effective radio architectures that need to be reliably realized. This panel session will explore the technologies being developed within the industry to enable this new field of communications. The strengths and weakness of each technology will be debated, and the viability of each to provide a compelling alternative to fiber will be determined. The panel will bring together leading device engineers with system providers to provide a complete overview of the state-of-the-art Gb/s communications and a road map for the future.
In this letter, the ambipolar transport properties of graphene flakes have been used to fabricate full-wave signal rectifiers and frequency-doubling devices. By correctly biasing an ambipolar graphene field-effect transistor in common-source configuration, a sinusoidal voltage applied to the transistor gate is rectified at the drain electrode. Using this concept, frequency multiplication of a 10-kHz input signal has been experimentally demonstrated. The spectral purity of the 20-kHz output signal is excellent, with more than 90% of the radio-frequency power in the 20-kHz frequency. This high efficiency, combined with the high electron mobility of graphene, makes graphene-based frequency multipliers a very promising option for signal generation at ultrahigh frequencies.
This letter presents a 60 GHz on-off keying demodulator in a 0.13 μm CMOS. The demodulator consists of a detector and a baseband amplifier and employs a gain-boosting technique for higher conversion gain. The measured conversion gain is 13.6 dB at -16 dBm of input power. The detector voltage re sponsivity is 2434 mV/mW, which is the highest value in a 60 GHz silicon-based demodulator. The demodulator consumes 14.7 mW, and the measured maximum data rate is 5 Gb/s. the energy per bit, which indicates energy efficiency, exhibits 2.94 pJ/b. To the best of our knowledge, this demodulator achieves the highest data rate and the lowest energy per bit of all published 60 GHz band OOK de modulators using silicon-based technology.
The combination of the unique properties of graphene with new device concepts and nanotechnology can overcome some of the main limitations of traditional electronics in terms of maximum frequency, linearity, and power dissipation. In this letter, we demonstrate the use of the ambipolar-transport properties of graphene for the fabrication of a new kind of RF mixer device. Due to the symmetrical ambipolar conduction in graphene, graphene-based mixers can effectively suppress odd-order intermodulations and lead to lower spurious emissions in the circuit. The mixer operation was demonstrated at a frequency of 10 MHz using graphene grown by chemical vapor deposition on a Ni film and then transferred to an insulating substrate. The maximum operating frequency was limited by the device geometry and the measurement setup, and a high-quality factor was observed with a third-order intercept point of +13.8 dBm.
We have achieved mobilities in excess of 200,000 cm2 V −1 s−1 at electron densities of ∼2 ×1011 cm−2 by suspending single layer graphene. Suspension ∼150 nm above a Si/SiO2 gate electrode and electrical contacts to the graphene was achieved by a combination of electron beam lithography and etching. The specimens were cleaned in situ by employing current-induced heating, directly resulting in a significant improvement of electrical transport. Concomitant with large mobility enhancement, the widths of the characteristic Dirac peaks are reduced by a factor of 10 compared to traditional, nonsuspended devices. This advance should allow for accessing the intrinsic transport properties of graphene.
Graphene transistors are of considerable interest for radio frequency (rf) applications. High-frequency graphene transistors with the intrinsic cutoff frequency up to 300 GHz have been demonstrated. However, the graphene transistors reported to date only exhibit a limited extrinsic cutoff frequency up to about 10 GHz, and functional graphene circuits demonstrated so far can merely operate in the tens of megahertz regime, far from the potential the graphene transistors could offer. Here we report a scalable approach to fabricate self-aligned graphene transistors with the extrinsic cutoff frequency exceeding 50 GHz and graphene circuits that can operate in the 1-10 GHz regime. The devices are fabricated on a glass substrate through a self-aligned process by using chemical vapor deposition (CVD) grown graphene and a dielectrophoretic assembled nanowire gate array. The self-aligned process allows the achievement of unprecedented performance in CVD graphene transistors with a highest transconductance of 0.36 mS/μm. The use of an insulating substrate minimizes the parasitic capacitance and has therefore enabled graphene transistors with a record-high extrinsic cutoff frequency (> 50 GHz) achieved to date. The excellent extrinsic cutoff frequency readily allows configuring the graphene transistors into frequency doubling or mixing circuits functioning in the 1-10 GHz regime, a significant advancement over previous reports (∼20 MHz). The studies open a pathway to scalable fabrication of high-speed graphene transistors and functional circuits and represent a significant step forward to graphene based radio frequency devices.
We demonstrate the growth of high quality graphene layers by chemical vapor deposition (CVD) on insulating and conductive SiC substrates. This method provides key advantages over the well-developed epitaxial graphene growth by Si sublimation that has been known for decades. (1) CVD growth is much less sensitive to SiC surface defects resulting in high electron mobilities of ∼1800 cm(2)/(V s) and enables the controlled synthesis of a determined number of graphene layers with a defined doping level. The high quality of graphene is evidenced by a unique combination of angle-resolved photoemission spectroscopy, Raman spectroscopy, transport measurements, scanning tunneling microscopy and ellipsometry. Our measurements indicate that CVD grown graphene is under less compressive strain than its epitaxial counterpart and confirms the existence of an electronic energy band gap. These features are essential for future applications of graphene electronics based on wafer scale graphene growth.
We describe monocrystalline graphitic films, which are a few atoms thick but are nonetheless stable under ambient conditions,
metallic, and of remarkably high quality. The films are found to be a two-dimensional semimetal with a tiny overlap between
valence and conductance bands, and they exhibit a strong ambipolar electric field effect such that electrons and holes in
concentrations up to 1013 per square centimeter and with room-temperature mobilities of ∼10,000 square centimeters per volt-second can be induced by
applying gate voltage.
This paper describes the development of a InP-HEMT MMIC chipset for 120-GHz wireless applications. The transmitter chip includes a frequency doubler for carriers, an ASK modulator, an RF band-pass filter, and a power amplifier. The receiver chip includes a low-noise amplifier and an ASK demodulator. A back-to-back test of the chipset has shown it to be fully functional at 10-Gbit/s data rate with BER=e-12 at -45.7-dBm input power of the receiver chip. To our knowledge, this is the first report of the development of highly integrated MMIC chipset operating at 120 GHz for wireless data communication.
Closed-form expressions are derived for the transfer
characteristic of a low-power monolithic RF peak detector. These are
compared with computer simulation and experimental measurements
20 Mb/s zero-power graphene-on-glass microwave envelope detectors for ubiquitous ultra-low-power wireless network
- J S Moon
- H C Seo
- K Ah Son
- B Yang
- D Le
- H Fung
- Adel Schmitz
J. S. Moon, H. C. Seo, K. Ah Son, B. Yang, D. Le, H. Fung, and Adel
Schmitz,"20 Mb/s zero-power graphene-on-glass microwave envelope
detectors for ubiquitous ultra-low-power wireless network", IEEE MTTS., pp 1-3, 2014.
A Subharmonic Graphene FET Mixer
- O Habibpour
- S Cherednichenko
- J Vukusic
- J Stake
O. Habibpour, S. Cherednichenko, J. Vukusic, and J. Stake," A
Subharmonic Graphene FET Mixer," IEEE Electron Device, vol. 33, No.
1, 2012.