Franco Giannini

University of Rome Tor Vergata | UNIROMA2 · Centro di Ingegneria delle Microonde per applicazioni Spaziali

Parkinson’s disease (PD) is a chronic neurodegenerative disorder with high worldwide prevalence that manifests with muscle rigidity, tremor, postural instability, and slowness of movement. These motor symptoms are mainly evaluated by clinicians via direct observations of patients and, as such, can potentially be influenced by personal biases and in...

Parkinson’s disease (PD) is responsible for a broad spectrum of signs and symptoms, including relevant motor impairments generally rated by clinical experts. In recent years, motor measurements gathered by technology-based systems have been used more and more to provide objective data. In particular, wearable devices have been adopted to evidence d...

Objective: In order to evaluate Parkinson disease patients response to therapeutic interventions, sources of information are mainly patient reports and clinicians assessment of motor functions. However, these sources can suffer from patients subjectivity and from inter/intra raters score variability. Our work aimed at determining the impact of wea...

Early noninvasive reliable biomarkers are among the major unmet needs in Parkinson's disease (PD) to monitor therapy response and disease progression. Objective measures of motor performances could allow phenotyping of subtle, undetectable, early stage motor impairments of PD patients. This work aims at identifying prognostic biomarkers in newly di...

Healthy and pathological human walking are here interpreted, from a temporal point of view, by means of dynamics-on-graph concepts and generalized finite-length Fibonacci sequences. Such sequences, in their most general definition, concern two sets of eight specific time intervals for the newly defined composite gait cycle, which involves two speci...

This paper presents a 4-way combined G-band power amplifier (PA) fabricated with a 130-nm SiGe BiCMOS process. First, a single-ended PA based on the cascode topology (CT) is designed at 185 GHz, which consists of three stages to get an overall gain and an output power higher than 27 dB and 13 dBm, respectively. Then, a 4-way combiner/splitter was d...

Power amplifiers (PAs) are the most power-consuming devices in a transmitter. Their performance in efficiency is crucial to the efficiency of the whole system. Therefore, the issue of high efficiency PA has remained hot over the years. This paper presents an approach to design an S-band single stage class-F PA biased in class-C condition. Through t...

Currently, clinical evaluation represents the primary outcome measure in Parkinson's disease (PD). However, clinical evaluation may underscore some subtle motor impairments, hidden from the visual inspection of examiners. Technology-based objective measures are more frequently utilized to assess motor performance and objectively measure motor dysfu...

Background Technology-based objective measures (TOMs) recently gained relevance to support clinicians in the assessment of motor function in Parkinson’s disease (PD), although limited data are available in the early phases. Objective To assess motor performances of a population of newly diagnosed, drug free PD patients using wearable inertial sens...

In this paper, we report a high-performance balun with characteristics suitable for future broadband sub-THz differential circuits. The idea of the balun is based on three asymmetric coupled lines, which enhance the odd mode capacitances to equalize the even/odd mode phase velocities. The inner line of the three asymmetric coupled lines is configur...

In this work, we present a novel multisensory electronic architecture that can work with very low voltage requirements thus enabling power management directly from harvesting-based low-voltage sources. The harvesting system here proposed relays on thermoelectric generator cells useful for furnishing additional power to an electronic system made of...

Tetraplegic people need continuous assistance in every daily activity. Assistive technologies can improve, to a certain degree, their quality of life allowing partial autonomy with powering their residual capability of movements. In this work, we propose a novel wire-free low-cost user-friendly battery-operated sensory headwear, which allows home a...

Objective: The complex nature of Parkinson's disease (PD) makes difficult to rate its severity, mainly based on visual inspection of motor impairments. Wearable sensors have been demonstrated to help overcoming such a difficulty, by providing objective measures of motor abnormalities. However, up to now those sensors have been used on advanced PD...

Developmental coordination disorder (DCD) and attention-deficit hyperactivity disorder (ADHD) are neuro-developmental disorders, starting in childhood, which can affect the planning of movements and the coordination. We investigated how and in which measure a system based on wearable inertial measurement units (IMUs) can provide an objective suppor...

This paper proposes a design method to minimize the phase distortion (AM/PM) in Gallium Nitride (GaN) Power Amplifiers (PAs), without significantly worsening other key features such as efficiency, amplitude distortion and gain. The design strategy consists in the adoption of a smart two-stage architecture, in which the driver stage is devised to ac...

This paper presents the theoretical analysis of phase distortion (AM/PM) mechanisms in Gallium Nitride (GaN) Doherty power amplifiers and a novel approach to optimize the trade-off between linearity and efficiency. In particular, it is demonstrated how it is possible to mitigate the AM/PM by designing a suitable mismatch at the input of the active...

Starting from the mathematical bases of waveform engineering, this contribution demonstrates the effectiveness of class-F power amplifier design in different bias conditions, provided the correct harmonic content is presented at the input. To validate the theoretical assumptions, low-frequency multiharmonic load-pull measurements are carried out on...

This contribution reports the design of an X-band MMIC power amplifier in a 0.25 um GaN technology, proposing for the first time a harmonic manipulation approach on a class C bias condition. Output network provides the power matching condition at fundamental frequency and an open circuit condition at the 3rd harmonic; the correct phase ratio betwee...

This chapter describes the methodologies and approaches used to design power amplifiers (PAs) for high-frequency applications. The available technologies and their pros and cons are discussed in detail. Particular attention is devoted to highlight the PAs’ characteristics in relation to device properties and to link the modeling aspects to the avai...

In this paper, we report the preliminary results of an Engineering Model of a complete SSPA, developed for Galileo satellite system (E1 band, 1575.42 MHz), and based on UMS GaN (GH50-10) technology. The SSPA includes also satellite interfaces (e.g., internal power supply generation unit, telemetry and telecommand functionalities) and measured resul...

In this paper, authors present the preliminary measurements of a PWM-based transmitter. It is realised by cascading a pulse width modulator and a driver stage (PWCD), with a high efficiency Class E switched mode power amplifier (SMPA). The PWCD was realized by using 250nm BiCMOS process from IHP (SGB25V GD), while the SMPA was realized by using a p...

The guidelines for designing a high efficiency and low distortion 2-stages Gallium Nitride (GaN) power amplifier (PA) are presented. In particular, the developed approach to mitigate the phase distortion (AM/PM) without worsening the efficiency and gain features is adopted to design a 7GHz PA based on 0.25 µm GaN process from TriQuint. When tested...

This paper describes the development of an L-Band (f 0 = 1.575 GHz) high power and efficient solid state power amplifier (SSPA) designed for the European satellite navigation system (i.e. Galileo). The amplifier, developed in the framework of the European Project named SLOGAN, exploits the GH50-10 GaN technology available at United Monolithic Semic...

This chapter describes the methodologies and approaches used to design power amplifiers (PAs) for high-frequency applications. The available technologies and their pros and cons are discussed in detail. Particular attention is devoted to highlight the PAs' characteristics in relation to device properties and to link the modeling aspects to the avai...

A combined class-AB and a Doherty power amplifier conceived for microwave backhaul in the 7 GHz frequency band are here presented and compared. They are fabricated in the same GaN monolithic process and have identical total active device periphery. For the given application, the linearity-efficiency trade-off for the two architectures is discussed....

A novel design methodology for two stages microwave monolithic integrated circuit (MMIC) power amplifier (PA) is presented. The proposed solution allows to almost null the phase distortions (AM/PM) without worsening other key features of the PA, such as amplitude distortion (AM/AM) and efficiency. The derived approach is verified presenting the des...

This contribution aims at the experimental confirmation of the advantages of the harmonic manipulation theory, using a low-frequency low-cost characterization setup. A 0.5-µm 10x100-µm (1-mm gate periphery) GaN HEMT has been characterized synthesizing at the current-generator plane different load conditions, realizing tuned-load and Class-F operati...

Doherty Power Amplifier (DPA) is an old and fashionable configuration, introduced by W.E. Doherty in 1936 at the Bell Telephone Laboratories (BTL) of Whippany, New Jersey, for the realization of vacuum tube high-efficiency amplifiers. The original configuration has been successfully resurrected in the last decade. Actually, the proposed solution ha...

This paper investigates the effect of the application of a window based Crest Factor Reduction (CFR) technique in conjunction with Volterra based Digital Predistortion (V-DPD) technique method on a Doherty power amplifier (DPA). Spectra regrowth, Peak to Average Power Ratio (PAPR) reduction and Error Vector Magnitude (EVM) have been used to evaluat...

This paper describes the development of an L-Band (f 0 = 1.575GHz) high power and efficient amplifier designed for the European satellite navigation system (i.e., Galileo). The amplifier, developed in the framework of the European Project named SLOGAN, exploits the GH50-10 GaN technology available at United Monolithic Semiconductor foundry. The req...

The design, realization and test of a tri-band concurrent Doherty power amplifier (DPA) is presented. The prototype has been realized in hybrid technology using GaN HEMT devices. The operating bands have been selected around the following carrier frequencies f 1 = 1.84GHz, f 2 = 2.14GHz and f 3 = 2.65GHz corresponding to LTE, UMTS and WiMax applica...

In this work, the design of a C-band class-AB power amplifier based on the waveform engineering approach is presented. The design leverages the low-frequency characterization of the transistor to obtain the prediction of its optimum operating condition. An exhaustive validation of the realized amplifier fully validates the proposed design technique...

In this work, the design of a C-band class-AB power amplifier based on the waveform engineering approach is presented. The design leverages the low-frequency characterization of the transistor to obtain the prediction of its optimum operating condition. An exhaustive validation of the realized amplifier fully validates the proposed design technique...

This paper presents the design of a concurrent tri-band Doherty Power Amplifier (DPA) for 1.84 GHz, 2.14 GHz and 2.65 GHz frequency bands. The frequency response around each operating band is maximally flattened adopting a new design strategy. The DPA is based on hybrid technology using two 8 W GaN HEMT as active devices. The results show a peak of...

The benefits of using source field plate (FPS) in AlGaN/GaN HEMTs to reduce the phase distortion in efficient power amplifiers (PAs) is demonstrated in this contribution. The link between phase distortion of a PA and the drain-to-gate feedback parasitic capacitance of the transistor is shown. This link leads to critical phase nonlinearity expeciall...

This article is dedicated to the hybrid microwave power amplifiers and to their design. It aims at giving an overview of the topic as complete as possible, although it does not expect to be exhaustive, given the complexity of the subject. Thus, an attempt was made to collect any useful information about hybrid power amplifiers from the designer's p...

This paper presents an innovative architecture to drastically enlarge the bandwidth of the Doherty power amplifier (DPA). The proposed topology, based on novel input/output splitting/combining networks, allows to overcome the typical bandwidth limiting factors of the conventional DPA. A complete and rigorous theoretical investigation of the develop...

This letter presents the design and characterization of an ultra-broadband GaN Doherty amplifier with more than an octave bandwidth. The developed architecture is based on ultra-wideband input/output splitting/combining networks capable to mitigate the typical frequency limiting factors of the traditional Doherty amplifier. The innovative design ap...

In this paper, an experimental validation about the benefit of the input harmonic manipulation on the performance of a microwave power amplifier is presented. With the support of low-frequency measurements on a 0.5×1000 μm2 GaN HEMT, the importance of synthesizing the correct input waveform at the intrinsic section of the device is highlighted. A c...

Phase Shifted Transmitter (PST) operates without mixers and allows the direct generation and transmission of any envelope and phase-modulated signals. Besides of maintaining all the benefits of the standard PST architecture, the solution here proposed allows the integration of an energy recovery circuit capable to boost the efficiency of the overal...

In this paper, an experimental validation about the benefit of the input harmonic manipulation on the performance of a microwave power amplifier is presented. With the support of low-frequency measurements on a 0.5×1000 μm2 GaN HEMT, the importance of synthesizing the correct input waveform at the intrinsic section of the device is highlighted. A c...

This contribution presents the analysis, design and characterization of a high gain Doherty power amplifier implementing an integrated Driver stage in the Auxiliary branch. Guidelines and design equations are demonstrated, fulfilling the full integration of the whole new architecture. The development of a microwave monolithic integrated circuit pro...

The mechanisms leading to higher phase distortion of Doherty power amplifiers in comparison to standard architectures are theoretically investigated and experimentally verified. The analysis focuses on the Main amplifier contribution to AM/PM due to the load modulation, a key feature of the Doherty, and is based on a simplified active device circui...

This contribution presents a ground breaking distributed matching/combining network that allows to develop ultra-broadband Doherty Power Amplifiers (DPAs). In 73% of fractional bandwidth, from 1.2 GHz to 2.6 GHz, input return loss lower than -18 dB is demonstrated with 1.82 resistance transformation ratio. The active load modulation capability is v...

In this paper, the system level characterization and linearization of two GaN monolithic Doherty power amplifiers for 7 GHz backhaul transmitters is presented. In particular, the two different design techniques, aimed to reduce the gain penalty tipically affecting the Doherty topology, are briefly introduced. Both amplifiers can deliver more than 5...

The discrepancy between models and actual components sometimes causes the shift of the operating band of the realized circuit. This side effect is not acceptable and difficult to predict in many applications. This paper proposes a post-processing method to tune the frequency band of a hybrid Doherty power amplifier (DPA) after its implementation.

Closed-form relationships for the optimum bias point of high efficiency and widband power amplifiers (PAs) based on cascode cel are presented in this contribution. Through a rigorous analysis, the optimum output load, supply voltages, expected output power and efficiency of a cascode PA are derived and compared with those of the standard common sou...

The capability to control 'enabling technologies' is mandatory to overcome any restrictions on exports of critical components and therefore represents a strategic condition for the companies operating in military and aerospace market. In this scenario, Selex ES Foundry has developed and optimized GaN-HEMT process for manufacturing high power HPAs a...

The relationships between phase distortion, bias point and load modulation in power amplifiers are experimentally evaluated for two different GaN HEMT technologies. Measurements on devices with fixed and modulated load, to emulate the dynamic working conditions of the main stage of a Doherty amplifier, have been carried out through an advanced sour...

A GaN-MMIC power module for microwave back-haul applications in C-band frequency range is presented in this contribution. The design is based on a commercial 0.25 μm channel length GaN power process. The module is composed of two stages. The final stage is designed in order to reach 38 dBm of saturated output power with high efficiency and AM/AM li...

In this paper a characterization technique for the evaluation of transistor performance and restrictions is presented, based on a simple and low-cost measurement system. Experimental examples, carried out on a 0.5 × 1000 μm2GaN HEMT, are reported. The validity of the proposed approach is demonstrated by comparing the results with the ones obtained...

This contribution presents the development and characterization of a GaN Doherty power amplifier for backhaul microwave links in the 6.35–7.35 GHz frequency range. To minimize the AM/AM distortion, a driver stage is integrated in the auxiliary branch. Such feature also allows to obtain a higher overall gain than the standard approach. Moreover, to...

This paper evaluates the Doherty power amplifier architecture in terms of linearity, efficiency and design solutions. As case study four different prototypes are presented, one for 4G Picocells at 2.1 GHz, one for WiMax applications at 3.5 GHz and two for point-to-point microwave backhaul radiolinks at 7 GHz. Experimental results together with desi...

In this contribution, the design approach and the experimental results of an ultrawideband power amplifier in GaN technology is presented. The amplifier is designed in a single-ended configuration by using a 0.5 μm GaN HEMT with 1 mm gate periphery. The realized amplifier shows an efficiency higher than 40% with an output power greater than 36 dBm...

In this article, the design approach, the implementation, and experimental results of multiband branch-line couplers operating at arbitrary frequencies are presented. The conventional branch-line coupler structure is adapted to multiband operation by shunting its four ports with multiband reactive networks. The performance of the proposed multiband...

In this contribution, a design approach for the realization of broadband Doherty Power Amplifiers (DPAs) is proposed and demonstrated. The methodology is based on the exploitation of the wideband response of 2-sections branch-line couplers both as input splitter and output combiner of the DPA. These couplers are designed through a CAD optimization...

In this paper, a theoretical investigation of the causes of the AM/PM distortion in Doherty Power Amplifiers is presented for the first time. The distortion sources are identified and a solution to mitigate the AM/PM conversion through the input termination of the Carrier amplifier is also highlighted. The relevant analysis is carried out using a s...

This article is focused on GaN-based power amplifiers for applications up to 10 GHz. Several PAs developed in both MMIC and hybrid technologies for different RF and microwave frequency bands will be described. In particular, the designs of two ultra-wideband (UWB) PAs are reported together with experimental results. The first one is based on commer...

This letter presents the design and characterization of a novel wideband Doherty architecture. Both input splitter and output combiner are realized by means of two-sections branch-line alike couplers. The realized prototype based on commercial GaN active devices shows more than 36% of fractional bandwidth, from 1.67 to 2.41 GHz. In this frequency r...

This contribution describes the design, realization, and test of a compact X-band GaN MMIC high power amplifier (HPA) for synthetic aperture radar. The HPA represents the first step toward the realization of a fully integrated GaN transmitter/receiver (Tx/Rx) for X-band applications. The circuit is designed in a two stage configuration and it is fu...

The potentialities of GaN monolithic technology for the growing microwave backhaul power amplifier market are discussed in this paper. To support this discussion, two GaN monolithic Doherty power amplifiers for 7 GHz backhaul applications are presented. They exhibit 5 W output power, with almost 10 dB gain and high efficiency at 7 dB output power b...

This paper presents a complete and rigorous theoretical investigation of a Doherty architecture with a novel output combining network. The benefits in terms of bandwidth and feasibility held by the proposed topology are investigated and compared with the conventional one. In particular, the theoretical analysis demonstrates that the proposed output...