Electronics Letters

Published by Institution of Engineering and Technology and The Institution of Engineering and Technology
Online ISSN: 1350-911X
Publications
Article
Demonstrated are 1060 nm microelectromechanical-systems-based tunable vertical-cavity surface-emitting lasers (MEMS-VCSELs) with a 100 nm continuous tuning range under repetitively scanned operation at rates beyond 500 kHz and a 90 nm continuous tuning range under static operation. These devices employ a thin strained InGaAs multiple quantum well active region integrated with a fully oxidised GaAs/AlxOy bottom mirror and a suspended dielectric top mirror. The devices are optically pumped via 850 nm light. These ultra-widely tunable lasers represent the first MEMS-VCSELs reported in this wavelength range, and are ideally suited for application in ophthalmic swept-source optical coherence tomography.
 
Schematic illustrating cleaved fibre coupling scheme as well as separation of incoming/ outgoing light by WDM coupler
Article
Microelectromechanical-systems-based vertical-cavity surface-emitting lasers (MEMS-VCSELs) capable of a 150 nm continuous tuning range near 1310 nm are demonstrated. These devices employ a thin optically pumped active region structure with large free-spectral range, which promotes wide and continuous tuning. To achieve VCSEL emission at 1310 nm, a wide-gain-bandwidth indium phosphide-based multiple quantum well active region is combined with a wide-bandwidth fully oxidised GaAs-based mirror through wafer bonding, with tuning enabled by a suspended dielectric top mirror. These devices are capable of being scanned over the entire tuning range at frequencies up to 500 kHz, making them ideal for applications such as swept source optical coherence tomography and high-speed transient spectroscopy.
 
a. Supply current mirroring VCCS b. Quasi-complementary VCCS with current gain (composite of Figs. 2, 3, 4).
N-type 1:10 ratio mirror 
P-type 1:1 mirror At I OUT = 1 mA compliance range is − 12 V to − 1 kV, continuous power dissipation about 2 
Cascoded operational amplifier 20 V < HV+ < 0.8 kV, − 1 kV < HV − < − 20 V, continuous power dissipation (either rail) about 2 W. U1 = LT1351 (250 μ A supply current, 3 MHz bandwidth, 200 V/ μ s slew rate). 
Article
A voltage current convertor is described having a quasi complementary class AB architecture that is particularly suited to implementation using discrete power MOSFETs. High-voltage mirror designs are presented, enabling the construction of sources with kilovolt compliance range, tens of watts of output power and greater than 100 kHz bandwidth. GΩ output impedance and distortion below 1% can be obtained with no trimming or transistor matching.
 
Article
An explicit solution is given to a generic feedback design problem arising in flow control. The problem, which incorporates higher order dynamics and capacity constraints, captures important features of a number of design problems for units whose purpose is to smooth out flow rate fluctuations between interconnected devices
 
Article
An open-loop power control technique that establishes a linear relationship between a d.c. control voltage and the average load voltage is described. The output voltage is insensitive to input a.c. line voltage fluctuations as well as variations in supply frequency. The control output is versatile enough to drive a semiconductor on/off switch or an s.c.r. bridge operating either as a rectifier or as an inverter.
 
Article
A new algorithm for the construction of (0, 1)-code matrices based on the Greedy algorithm is proposed which allows the generation of code matrices with any desired matrix dimension and weight. Such codes are very useful in incoherent optical code-division multiple-access (CDMA) systems combining wavelength hopping and time spreading. So it is possible to achieve an auto-correlation function with zero sidelobes and an aperiodic cross-correlation function with a maximum value of one
 
Article
Superluminescent AlGaAs-GaAs diodes with 15 mW output power and 1% Fabry-Perot modulation depth and modules with 3 mW polarisation maintaining fibre output have been developed. At output powers of more than 8 mW the effect of saturation on power fluctuations was observed.
 
Article
An area- and power-efficient analogue adaptive equaliser (AEQ) is realised in a 0.13 m CMOS technology. The negative capacitance circuits are exploited at the equalisation filter to achieve wider bandwidth and larger high-frequency boosting, instead of using passive inductors that lead to a large chip area. Measured results demonstrate the data rate of 10 Gbit/s for 20 and 34 inch FR4 traces as channels, while dissipating only 6 mW from a single 1.2 V supply. The chip core occupies an extremely small area of 50 times 130 m<sup>2</sup>. To the best of the authors' knowledge, this chip achieves the lowest power consumption and the smallest chip area among the recently reported AEQs.
 
Article
Splices of single-mode fused silica fibre having strengths equivalent to that of the as-drawn fibre of ˜800 ksi (5.5 GPa) with a coefficient of variation v of ≪0.01 are produced by fusion splicing with an H<sub>2</sub>-Cl<sub>2</sub>-O<sub>2</sub> flame. These results demonstrate that fused silica fibre can be reheated to fusion temperatures and retain original high strength. The results are statistically analysed with respect to variations in breaking load, fibre and splice diameter, and relative humidity.
 
Programmable modes of operation
Measured performance summary
Measured PLL output jitter 
Article
A 533 MHz programmable phase-locked loop is designed for DDR applications using a switched current filter and implicit phase detection. The use of switched current technology allows a fully integrated loop filter which is much smaller than equivalent integrated passive filters, as a result the circuit occupies only 0.012 mm<sup>2</sup> on a 0.12 m 1.2 V digital CMOS process.
 
Article
We have realised an electronic device with the aim of improving the relative stability in voltage dV/V of an electrostatic generator (voltage 400 kV, current 4 mA). This stability rose to 2×10¿6 (from 2×10¿5 previously) within a frequency bandwidth of 0.03¿1000 Hz. This electronic device, placed between the earth of the high-voltage generator and the earth of the utilisation, is autonomous, i.e. it can be applied for all kinds of generators, of low, high or very high voltage, with currents up to about 100 mA. The gain in stability can only be fixed after knowing the real characteristics of the generator, which should be improved.
 
Article
A low-biased Mach-Zehnder modulator, optical amplification, and a high-power photodetector are employed to achieve all-photonic link gain as high as 44 dB over a transmission length of 40 km. The link has a 3 dB bandwidth of 6.25 GHz and a 20 dB noise figure.
 
Measured VGA gain against V BIAS AE V CTRL=2 , where V BIAS ¼ 1 V
Article
A simple single-stage variable gain amplifier that offers 86 dB of gain variation, consumes 1.4 mW, and occupies 0.07 mm<sup>2</sup> is introduced and shown to have the largest gain range, lowest power, and smallest chip size ever reported based on 0.18 mum CMOS technology. A new approximated exponential equation is proposed, which offers the largest dB-linear range compared to all previously-reported approximated equations
 
Article
The authors have demonstrated a strained InGaAs multiquantum well laser grown on an InAs<sub>0.08</sub>P<sub>0.92</sub> ternary substrate. The epitaxial structure was grown using metal organic vapour phase epitaxy (MOVPE). The InAsP wafers were characterised using room temperature photoluminescence, X-ray diffraction and X-ray topography. Pulsed power levels of 60 mW/facet at h=1.75 μm were measured at T=250 K. A characteristic temperature of T<sub>0</sub>=46 K was observed over a temperature range of 78-250 K
 
Article
The dependence of the barrier height ϕBn of Au-Ga1−xAlxSb Schottky barriers on x, the mole fraction of Al in the solid, has been measured. The data show that as x increases the values of ϕBn also increase. However, the measured barrier heights do not agree with those predicted by the ‘common anion’ rule. This result, coupled with other available data, indicates that the Au-Ga1−xAlxSb hole Schottky barrier height (ϕBn) is not independent of the Ga/Al cation ratio. © 1980, The Institution of Electrical Engineers. All rights reserved.
 
Article
The authors examine the high-frequency performance of a sub-0.1 mu m gate InAlAs/InGaAs HEMT with a thin InAs layer inserted into the InGaAs channel. The transconductance is 2.1 S/mm and the current-gain cutoff frequency is 264 GHz using a 0.08 mu m-long gate.
 
Article
The authors show that the profiles of gate grooves can be effectively manoeuvered by the selection of surface metals of ohmic electrodes. The Ni surface metal is advantageous over Pt, since the recess etching is independent of materials and is more spatially homogeneous. These different etching behaviours and resulting gate-groove profiles are attributed to the existence of electrochemical effects during recess etching
 
Article
A vertical MOSFET with a channel length of 85 nm has been fabricated by molecular beam epitaxy. Compared to previous work, the electrical behaviour has been greatly improved, allowing the use of standard simulation tools for analysing the I-V characteristics. From experimental and theoretical results. We conclude that for vertical MOSFETs. The useful minimum channel length is not limited by the technological constraints but by the physical limits of the electrical performance. The useful minimum channel length is estimated to be ~80 nm
 
HEMT starting material
HEMT drain characteristics
Article
AlSb/InAs HEMTs with a 0.1 μm gate length have been fabricated with a thin InAs subchannel separated from the InAs channel by 30 Å of AlSb. As a result, these HEMTs exhibit improved charge control and a higher current-gain cutoff frequency. The devices have a microwave transconductance of 850 mS/mm and an f<sub>T</sub> of 180 GHz at V<sub>DS</sub>=0.6 V. After subtracting the gate bonding pad capacitance, an f<sub>T</sub> of 250 GHz was obtained
 
Article
A W-band divide-by-3 frequency divider with wide bandwidth and low power dissipation is presented using harmonic injection-locking technique. A cascode FET is employed for a self-oscillating second-harmonic mixer which is injection-locked by third-harmonic input to obtain the division order of three. The fabricated frequency divider using 0.1 μm GaAs metamorphic HEMT technology shows superior performance such as large bandwidth of 6.1 GHz around 83.1 GHz (7.3%) under small DC power consumption of 12 mW.
 
Article
Losses as low 0.65 dB cm-1 (3 ¿m width) and 0.3 dB cm-1 (8 ¿m width) have been measured (¿ = 1.15 ¿m) in high-confinement (NA ¿ 0.45) GaAs/GaAlAs optical waveguides grown by MOCVD. The Fabry¿Perot loss measurement technique used in deduced to be accurate to ±0.1 dB cm-1. These are the lowest losses reported for gudies of high electro-optic merit in III-V materials.
 
Article
An accurate RF method using a linear regression of high-frequency Z-parameter equations at zero gate voltage is developed to extract resistances and inductances of sub-0.1 μm MOSFETs. Good agreement between the measured and modelled S-parameters is observed up to 30 GHz, verifying the accuracy of the RF method.
 
Article
AlGa/GaAs modulation-doped field-effect transistors (MODFETs) have been fabricated with `T' cross-section 0.1 μm gates using electron-beam lithography. A unity current gain cutoff frequency f <sub>T</sub> of 113 GHz has been measured for a spike-doped MODFET with a GaAs buffer. This is the highest measured f <sub>T</sub> reported to date for FETs of any kind
 
Article
A sensitivity analysis of 0.1 mu m MOSFETs to manufacturing fluctuations has been carried out. The analysis reveals that the electrical parameter sensitivity in deep submicrometre devices differs from the currently produced micrometre size devices, making a revision of the validity of conventional semiconductor manufacturing heuristics for future technology mandatory.
 
Article
A ytterbium sensitised thulium-doped blue upconversion ZBLAN fibre laser pumped at 1065 nm by a high power, diode pumped, double clad fibre laser is demonstrated. With a pump power of 2.8 W at 1065 nm, a blue output power of 106 mW at 482 nm is achieved
 
Article
The state of the art for a planar doped pseudomorphic Al<sub>0.2 </sub>Ga<sub>0.8</sub>As/In<sub>0.2</sub>Ga<sub>0.8</sub>As HEMT with a gate length of 0.1 μm is presented. The devices exhibit an extrinsic and intrinsic transconductance of 1070 and 1510 mS/mm. Respectively, a maximum current density of 550 mA/mm and a peak current gain cutoff frequency of 220 GHz. These results are the highest ever reported for HEMTs fabricated on GaAs substrates
 
Article
We have successfully realised a 0.1 μm T-gate pseudomorphic (Al <sub>0.5</sub>Ca<sub>0.5</sub>)<sub>0.5</sub>In<sub>0.5</sub>P/In <sub>0.2</sub>Ga<sub>0.8</sub>As/GaAs high electron mobility transistor (PM-HEMT) grown on a GaAs substrate by gas source molecular beam epitaxy (GSMBE). The electronic transfer and mobility of the (Al<sub>x</sub>Ga <sub>1-x</sub>)<sub>0.5</sub>In<sub>0.5</sub>P/In<sub>0.2</sub>Ga <sub>0.8</sub>As structure as functions of the aluminium composition have been studied. The ohmic contact has also been optimised. For a single-side doped structure, the devices exhibit the best RF and DC performances of the AlGaInP/InGaAs system with a current density of 430 mA/ mm and an extrinsic transconductance Gm of 550 mS/mm. The cutoff frequencies have been determined to be Ft=100 GHz and Fmax=160 GHz at Vds=1.5 V. These excellent performances clearly show the high-quality material grown by GSMBE
 
Article
An InP double hetero-junction bipolar transistor (DHBT) distributed power amplifier MMIC with 35 dB gain, 42 GHz bandwidth and 15 dBm output power is reported. This represents the highest power and largest gain reported over this bandwidth from a single chip HBT amplifier. A lumped preamplifier with a novel distributed output is used to obtain high gain and wide bandwidth at these power levels.
 
Article
De-embedded high frequency (HF) noise parameters of Ge p-channel modulation doped field effect transistors (MODFETs) on a Si<sub>0.4</sub>Ge<sub>0.6</sub> virtual substrate have been determined for the first time. The 0.1 × 100μm devices have a minimum noise figure NF<sub>min</sub> = 0.3 dB (0.5dB) ± 0.2dB, a noise resistance R<sub>n</sub> = 95 Ω (90 Ω) ± 5 Ω, an optimum reflection coefficient Γ<sub>opt</sub> = 0.7 ∠ 6° and an associated gain G<sub>ass</sub> = 14 dB (13 dB) at 1.2 GHz (2.5 GHz), at a bias corresponding to the optimum unity current-gain frequency f<sub>T</sub> = 55GHz and the maximum oscillation frequency f <sub>MAX</sub> = 135GHz. Noise results are given in the 1.2-12GHz frequency range and 20-160 mA/mm current range
 
Article
Short channel effects are thoroughly investigated in sub-0.1 μm N channel SOI-MOSFETs by using a two-dimensional numerical simulation. Drain-induced barrier lowering and charge sharing effects are calculated as a function of the main device parameters for gate lengths down to 0.05 μm. The impact of the silicon layer, the gate oxide and the buried oxide thicknesses, as well as of the Si film doping, are shown
 
Article
An In<sub>0.53</sub>(Al<sub>x</sub>Ga<sub>1-x</sub>)<sub>0.47</sub>AS quaternary channel has been introduced into n<sup>+</sup>-InAlAs/InGaAs HEMTs. By adding a small amount of Al to the InGaAs channel, the bandgap can be enhanced, which provides a higher reversed gate-drain breakdown voltage. In addition, the associated impact ionisation process can be suppressed in these quaternary channels. These HEMTs have been demonstrated with a very low output conductance (4 mS/mm for x=0.2) and a much smaller gate leakage current than conventional InP-HEMTs
 
Article
The authors report on RF results of p-type Ge channel modulation doped field effect transistors (MODFETs) with a gate length of 1.0 μm. The structure was grown on a relaxed 4.9 μm thick compositionally graded Si<sub>0.4</sub>Ge<sub>0.6</sub> buffer. The devices exhibit DC transconductances up to 190 mS/mm and saturation currents up to 190 mA/mm. Cutoff frequencies of f<sub>T</sub> 59 GHz and f<sub>max</sub>=135 GHz have been obtained. The f<sub>max</sub> value is, to the knowledge of the authors, the highest reported so far for p-type Si-based devices
 
Article
It is shown that a further performance improvement in MODFETs with InAs-inserted channel structures can be achieved by properly designing the subchannel layer that lies directly under the main channel of the InAs layer. The use of an In<sub>0.30</sub>Ga<sub>0.70</sub>As layer grown with tensile strain on the InP substrate contributes to better accommodation of the 2D electron gas in the InAs layer. This translates to a >10% increase in the maximum extrinsic transconductance and an 8% increase in the current gain cutoff frequency of a 0.1 μm device
 
Article
We have developed a separated absorption and multiplication (SAM) avalanche photodiode (APD) with the thinnest reported InAlAs multiplication layer of 0.1 μm and achieved 18.8 V operation. With high speed and a high GB product of 140 GHz. This makes it possible to realise a compact 10 Gbit/s APD receiver
 
Article
The AM and FM response of an erbium-doped fibre amplifier has been characterised for signal modulation frequencies in the range 130 MHz to 15 GHz. Both the amplifier gain and phase are found to be constant for both amplitude-modulated and frequency-modulated signals.
 
Article
It is shown that the threshold-voltage uniformity of 0.1 μm InAlAs/InGaAs-based modulation-doped field-effect transistors with different numbers of gate fingers and different gate widths can be improved when a thin cap-layer structure is employed. This improvement is based on the reduction of the recess time. This reduction suppresses the difference in etching that results from the different etching rates caused by the different electrochemical effects that occur because of the varied gate layouts
 
Article
Cutoff frequencies are measured for sub-0.25 mu m-gate InAlAs/InGaAs/InP HEMTs fabricated with a novel T-gate process using ion-beam etching in conjunction with both electron-beam lithography and photolithography. The cutoff frequency of 200 GHz is demonstrated by 0.12 mu m-gate HEMT.
 
Article
The realisation of a millimetre-wave rectangular waveguide fabricated using traditional monolithic technology is presented. The rectangular waveguide has a cutoff frequency of 100 GHz and an operating frequency of 105 GHz. The measured performance clearly shows that the dominant TE<sub>10</sub> mode of propagation is supported
 
Article
Results are reported of high-transconductance p-channel MODFETs fabricated on Ge/Si<sub>0.4</sub>Ge<sub>0.6</sub> strained-layer heterostructures grown by UHV-CVD. Devices with 0.1 mm gate length were fabricated on compressively-strained pure-Ge channels with a Hall mobility of 1750 cm<sup>2</sup>/Vs (30900 cm<sup>2</sup>/Vs) at room temperature (T=77 K). These devices displayed room-temperature peak extrinsic transconductances as high as 317 mS/mm, at V<sub>ds</sub>=-0.6 V, while the output conductance under the same bias conditions was only 18 mS/mm, corresponding to a maximum voltage gain of 18. At T=77 K, peak extrinsic transconductances as high as 622 mS/mm were obtained at bias voltages as low as V<sub>ds</sub>=-0.2 V. To our knowledge, the 77 K transconductance is the highest ever reported for a p-type field effect transistor
 
Article
0.1 μm Ga<sub>0.51</sub>In<sub>0.49</sub>P/In<sub>0.2</sub>Ga <sub>0.8</sub>As/GaAs PHEMTs grown by GSMBE have been realised. A new interface GaInP/InGaAs has been studied and optimised to give a 2-DEG density of 2×10<sup>12</sup> cm<sup>-2</sup> with a mobility of 5500 cm<sup>2</sup>/Vs at 300 K. The AuGe/Ni/Au ohmic contact has been also optimised (R<sub>c</sub>=0.08 Ω mm) and a new nonselective wet chemical etching technique based on iodic acid (HIO<sub>3</sub>) has been developed. This device with single δ-doping exhibits state of the art DC and RF performances in this new system with a current density of 780 mA/mm, a breakdown voltage of 9 V a G<sub>m</sub> of 700 mS/mm and an F<sub>t</sub> of 120 GHz
 
Article
In<sub>0.32</sub>Al<sub>0.68</sub>As/In<sub>0.33</sub>Ga<sub>0.67 </sub>As HEMT structures were grown by molecular beam epitaxy (MBE) on GaAs substrates. An inverse step metamorphic buffer (IS) was used to reach a relaxation rate close to 98% and a mean cross-hatch of 2 nm. This structure, which has a gate length of 0.1 μm, exhibits a peak transconductance of 750 mS/mm and a current density of 650 mA/mm. A current gain cutoff frequency F<sub>t</sub> of 160 GHz and a maximum oscillation frequency F<sub>max</sub> of 400 GHz were also obtained. These results clearly demonstrate the good electron transport properties due to the high relaxation rate and the good filtering of dislocations
 
Article
A new RF method based on the accurate extraction of the intrinsic transconductance and gate-source channel capacitance from measured S-parameters is proposed to determine the intrinsic cutoff frequency of sub-0.1 mu m MOSFETs. Using the RF technique, the intrinsic cutoff frequency enhancement with the linear dependence on I/L-poly(2) is observed in sub-0.1 mu m bulk n-MOSFETs. It is also observed that the reduction of extrinsic charging time is the most important to increase the measured cutoff frequency in sub-0.1 pal CMOS devices.
 
Article
The authors report an all solid state, VLSI compatible, electroluminescent device based on porous silicon with an external quantum efficiency greater than 0.1%, under CW operation. The emission, which is broadband and peaks at 600 nm, is detected above a low threshold current density and voltage of 0.01 Am<sup>-2</sup> and 2.3 V, respectively
 
Experimental system 
shows the results for the 32 different channels. Note that fifteen of the wavelengths were not controlled over the full range from 10 to 60 C owing to the current limits on the different sections of the particular laser used. However, all channels could be maintained stable within 0.1 nm from 10 to 40 C, and their wavelength did not move by more than 0.1 nm. 
Measurement of laser stability for 1537 nm channel 
Article
Experimental results are reported for a coolerless wavelength division multiplex (WDM) source. Simple quadratic trends extracted from the laser tuning characteristics are used to stabilise the wavelength for 32, 100 GHz-spaced, channels. Wavelength accuracy of <0.1 nm was maintained over a temperature range of up to 50degC, limited by the lasers used in this work
 
Article
The authors present the results of device modelling and circuit simulation of recently reported sub-0.1 μm nMOSFET devices and obtain excellent agreement with experimental data both at 300 K and at cryogenic temperatures. The approach accurately describes the subthreshold regime, short channel effects, and the notoriously difficult knee region of the characteristics, making the model suitable for deep submicrometre integrated circuit simulation
 
Article
Maximum oscillation frequency f<sub>MAX</sub> as high as 188 GHz at 300 K and 227 GHz at 50 K are reported for a 0.1×30 μm<sup>2</sup> n-type strained Si/Si<sub>0.6</sub>Ge<sub>0.4</sub> modulation doped field-effect transistor (n-MODFET) together with high quality DC characteristics. These f<sub>MAX</sub> are the highest values reported so far for Si-based hetero-FETs. The frequency performances are discussed using analytical expressions of f<sub>MAX</sub> and f<sub>Ti</sub> (intrinsic current gain cutoff frequency) together with the main equivalent circuit elements extracted.
 
Article
A serially concatenated code is presented which exhibits a turbo cliff at 0.28 dB. The concatenation consists of an outer rate one-half repetition code and an inner rate one recursive convolutional code. The iterative decoding scheme was designed using the extrinsic information transfer chart (EXIT chart)
 
Article
Oxides have been grown on n-type Ga1-xInxAs/GaAs wafers (x = 0.35 and 0.10) using plasma anodisation. According to C/V measurements, the surface can be biased into inversion and probably accumulation on Ga0.65In0.3SAs. The interface trap density is about 10¹² cm⁻²eV⁻¹ near midgap, and about 10¹³ cm⁻²eV⁻¹ near Hatband. MOS capacitors on Ga0.90In0.10As exhibit a high density of interface states 0.4-0.5 eV below the conduction band. © 1982, The Institution of Electrical Engineers. All rights reserved.
 
Article
A 10 GHz ring voltage controlled oscillator (VCO) has been designed and implemented in 0.12 μm CMOS technology. A source capacitively coupled current amplifier (SC3A) is adopted to realise this VCO. It can operate from 8.4 GHz up to 10.6 GHz with a phase noise of about -85 dBc/Hz at 1 MHz frequency offset. With the 1.5 V supply voltage, the current consumption is about 35 mA.
 
Article
A comparator, fabricated in a 1.5 V/0.12 mum CMOS process, is presented. The commonly separated reset and active-load transistors of typical comparators are combined. In the input part two NMOS transistors are added to reduce power consumption. At a supply voltage of 0.5 V the comparator works at a maximal clock of 600 MHz and consumes 18 muW
 
Top-cited authors
Trung Q. Duong
  • Queen's University Belfast
Hans-Jürgen Zepernick
  • Blekinge Institute of Technology
Vo Nguyen Quoc Bao
  • Posts and Telecommunications Institute of Technology
Hendrik Rogier
  • Ghent University
Sam Agneessens
  • Ghent University