Linear Amplifier Research Articles

Switch-Mode MOSFETs for Class A Radio Frequency Amplification

Vertical double diffused MOSFETs (“VDMOSFETs”) developed for switching power supplies were successfully used in high voltage, high frequency linear amplifier circuits. These high voltage power switches are surprisingly useful for linear RF power amplifiers and transmitters. In most of their intended applications such as in switching power supplies or switched digital amplifiers, VDMOSFETs are pulsed by a high voltage and the pulsed output is heavily filtered. This avoids the linear region of the VDMOSFET, which normally limits the efficiency to a theoretical maximum of 25%. However, in a search of MOSFETs for high voltage linear amplification using Class A bias without heavy use of filtering, these low-cost switching MOSFETs were found to work best, if limited to radio frequencies above 1.5 MHz. Conditions, and in particular, very low impedance driving of the MOSFET gate, were discovered that gave efficiencies of 70%, rivaling that of non-linear pulse techniques such as Class C or Class D operation. The beneficial effect of linear operation combined with high efficiency at a high voltage is suggested to arise from Miller capacitance. This was only seen at radio frequencies and with the larger current, higher gate capacitance devices. Switching MOSFETs as described here should be considered alongside dedicated RF MOSFETs such as the more expensive LD (lateral diffused) MOSFET when working with RF power.

Design and Evaluation of a High Quality Hybrid Current Multilevel Converter

This paper presents and discusses the design and evaluation a switched-linear current converter with its output voltage controlled suitable to high power applications. The proposed structure allows to build from a voltage source inverter that combines different semiconductors, operating at different frequencies, associated with a linear amplifier, in order to increase the output signal quality of its processed power without to penalize the volume of the passive filters. The system feedback control of the output voltage, eliminate ripples and its harmonics, sharing the current among each inverter leg, setting set individually current levels and its limits, defines operating ranges for each inverter, and mitigating the current which flows among each inverter branch. This proposal establishes an expandable configuration which operates even under failure in either converter and minimizes the total losses in to the linear converter. In addition, the structure allows to suppress the output filter capacitor. The system combination of the linear amplifier produces excellent output signal quality and fast dynamic responses. Examples of a projects are made performed, simulated and built to present the behavior and characteristics of the proposed hybrid converter.

A Series-Parallel-Form Switch-Linear Hybrid Envelope Tracking Power Supply With Two Multilevel Converters Sharing a Voltage-Level Provider

Series-parallel-form switch-linear hybrid envelope tracking power supply is composed of a voltage-controlled linear amplifier (VLA), a voltage-controlled switched-mode converter (VSC) and a current-controlled switched-mode converter. When the VLA adopts a class AB linear amplifier, an additional VSC can be added to be in series with the bottom transistor of the VLA to reduce its voltage drop. In order to reduce the system complexity, this article proposes to employ multiple bidirectional converters to implement the voltage-level provider, for being shared by the two VSCs, which are implemented with multilevel converters. Then, the loss model of the system is established, and based on which, an optimized design of the voltage-level number and voltage-level values of the multilevel converters is presented for improving the overall system efficiency. Finally, a prototype is fabricated aiming for tracking the envelope signal with 10-MHz bandwidth, 9.6–26.4-V output voltage, and 20-W average output power. The measured system efficiency is 78.79%, an improvement by 2.58% with the additional VSC.

SOA Enabled Self-Homodyne Coherent Bidirectional Transmission for Metro-Datacenter Interconnects

Self-homodyne coherent bidirectional (SHC-BiDi) scheme has gained much attention as a promising coherent-lite solution for datacenter interconnects (DCIs) recently. However, the twofold propagation loss of parallelly delivered signal and remote local oscillator (LO), as well as the power split loss of laser, severely restrict its power budget, making it inapplicable for metro-DCI networks until now. In this work, we propose a reach-extended, cost-efficient SHC-BiDi scheme suitable for metro-DCI applications. Thereinto, two bidirectionally operated semiconductor optical amplifiers (SOAs), with the signal gain clamped by counter-propagating remote LO, are utilized to simultaneously achieve linear signal amplification and remote LO regeneration. We comprehensively investigate the bidirectionally operated gain-clamped SOA and reach-extended transmission. The results show that the SOA can be transformed into a linear booster signal amplifier by clamping LO at proper power, while long-wavelength clamping reduces the nonlinear distortions of signal more efficiently. Besides, despite the potential cross-phase modulation (XPM) impairments on regenerated LOs, its induced Q <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> factor penalty can be kept below 0.570 dB, when the signal power and LO power injected into the SOA are below -10 dBm and above 0 dBm, respectively. Furthermore, by utilizing the built-in dithers of lasers to suppress the stimulated Brillion scattering (SBS) in LO propagation, successful 400G dual-polarization 16QAM transmissions are demonstrated over 50km and 75km links, with the corresponding transmitter laser power of 13.7 dBm and 18.5 dBm. Wherein, the digital signal processing (DSP) employing simple maximum likelihood (ML) phase recovery is also validated to be feasible under ∼1MHz laser linewidth.

A 29.5 dBm OOB IIP3 TIA Based on a Two-Stage Pseudo-Differential OTA With R-C Compensation and Cascode Negative Resistance

This paper presents a highly linear and wideband transimpedance amplifier (TIA) suitable for 5G Sub-6 GHz surface acoustic wave (SAW) filter-less receivers (RX). It is known that for the baseband TIA in a SAW-less RX, the high out-of-band (OOB) linearity is necessary to cope with huge OOB blockers. In other words, the input impedance ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Z_in</i> ) of the TIAs should be as low as possible, which in turn necessitates high-gain, large-bandwidth (BW) operational transconductance amplifiers (OTA). In this work, a pseudo-differential two-stage OTA with 46 dB open-loop gain and 1 GHz unity-gain loop bandwidth (UGLB) is designed at low supply voltage (Vdd). To stabilize the differential mode (DM) loop, the phase margin (PM) is compensated with the zeros generated by the series of resistors and capacitors (R-C), and the gain margin is improved by the feed-forward technique. To stabilize the common mode (CM) loop without the degradation of the DM gain, a wideband common mode rejection (CMR) technique named cascode negative resistance (CNR) is proposed. This TIA prototype is implemented in a 40 nm low-power (LP) CMOS technology. The measured results show that the TIA achieves 56 MHz BW and 29.5 dBm OOB IIP3. The input impedance is below 29Ω in the concerned frequency range and the in-band (IB) input referred noise (IRN) is 120 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">uV_RMS</i> . The total chip power consumption is around 8.5 mW at 1.2 V supply voltage and the core area is as small as 0.015 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mm</i> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

Effect of CNT Parameter Variations on CNTFET Amplifier Performance

In this paper we propose a procedure to study the dependence of a CNTFET amplifier performance on CNT parameters that fully identify the geometrical properties of a regular CNT. In particular these parameters are the length and structural indices (n,m) of CNT. We analyse the effects on a linear common source amplifier using a N type CNTFET with a resistive gate polarization. We polarize at a fixed drain voltage and current, gradually changing the CNT parameters. As regards the indices, we present the analysis for a zig-zag CNT. However the proposed procedure can be applied to other types of CNT. We show the effect on gain, on the 3 dB cut off frequency, F3dB, on the input and output resistances, obtaining that F3dB has a clear inverse dependence on the length and that also decreases at higher structural indices for zig-zag CNT.

Physics Informed Spiking Neural Networks: Application to Digital Predistortion for Power Amplifier Linearization

Physics Informed Spiking Neural Networks: Application to Digital Predistortion for Power Amplifier Linearization

DC-10 GHz broadband linear power amplifier for 5G applications using 180 nm CMOS technology

This article suggests a broadband linear power amplifier (PA) for DC-10 GHz for Fifth-generation (5G) and multi-standard applications using 180 nm CMOS technology. The suggested radio frequency power amplifier is appropriate for wideband LTE, IoT, WSN, multi-standard, and 5G radio frequency transmitters. T-coil peaking and bridged-shunt-series peaking amplifiers are used for bandwidth extension and gain flatness. Also, the interstage matching inductors between common source and common gate transistors are applied to improve radio frequency achievement. The suggested PA consists of four stages as follows; input stage, two stages using the T-coil peaking technique, and the last stage utilizing bridged-shunt-series peaking topology. The input stage is a complementary current reuse (CCR) common gate with active shunt feedback (SFB) architecture. It is utilized to extend the matching of RF input impedance with agreeable linearity and power gain at little power consumption. The second stage works in class-C operation to enhance the efficiency and reduce DC power consumed whereas the class-AB mode is utilized in the third and fourth stages to improve the output power. The suggested PA obtains a peak constant power equal to 14.25 dBm, a maximum Power-Added-Efficiency (PAE) of 16 %, and a peak gain equal to 22 dB. The proposed power amplifier dissipates a DC power of 80 mW. The die size of the proposed power amplifier equals 1mm2, whereas the total chip size includes the pads is 1.62mm2.

Stimulated Emission of Superradiant Atoms in Waveguide Quantum Electrodynamics

We investigate the stimulated emission of superradiant atoms coupled to a waveguide induced by a coherent-state photon pulse. We provide an analytical result when a short $\ensuremath{\pi}$ pulse is incident, which shows that the atoms emit photons coherently into the output pulse, which remains a coherent state in the short pulse limit. An incident pulse is amplified in a phase-preserving manner, where noise is added almost entirely in the phase direction in phase space. This property improves the ratio of the intensity signal to noise after the amplification for sufficiently short pulses. This is a unique feature different from general phase-preserving linear amplifiers, where the signal-to-noise ratio deteriorates in the amplification process. We also discuss the dependence of the photon-emission probability on pulse parameters, such as the pulse area and the duration.

High Bandwidth Series-Form Switch-Linear Hybrid Envelope Tracking Power Supply With Reduced Bandwidth Envelope and Step-Wave Edge Adjustment Methods

The series-form switch-linear hybrid envelope tracking (ET) power supply is constituted by a multilevel converter and a linear amplifier connected in series, featuring high efficiency and wide tracking bandwidth. With the development of wireless communication, the envelope bandwidth of the radio-frequency signal reaches tens of megahertz and even hundreds of megahertz, leading to a high switching loss in the multilevel converter and thus degraded overall efficiency of the ET power supply. To reduce the switching loss and ensure high tracking bandwidth, this article proposes to let the multilevel converter track the reduced bandwidth envelope signal and the linear amplifier track the original one. Then, a step-wave edge adjustment method is proposed to adjust or eliminate the rising and falling edges of the step-wave voltage for further reducing the equivalent switching frequency of the multilevel converter and the voltage across the power device of the linear amplifier. As a result, the switching loss in the multilevel converter and the power loss in the linear amplifier could be reduced, leading to a notably higher overall efficiency. A prototype with 40 MHz tracking bandwidth, 7–27 V output voltage, and 15 W average output power is fabricated and tested in the lab, and the experimental results are provided to verify the effectiveness of the proposed method.

Low-Complexity Adaptive DPD: From Online Optimization to Meta-Learning

In this paper, we investigate low-complexity and adaptive digital predistorsion (DPD) techniques in order to enhance wireless communication system latency, complexity and power consumption. Specifically, we introduce efficient meta-learning based solutions for time-varying power amplifier (PA) linearization that allow to reduce hardware complexity. Our first proposed solution consists in a meta-learning based neural network (NN) model that is capable to perform, offline, an optimal initialization of the NN based DPD. This leads to an efficient and fast adaptation of the DPD to the time-varying PA characteristics, i.e., few shots are needed during online calibration. Interestingly, we introduced a different approach, referred to as DPD NN Weights Selector (DPDNNWS), that offers the ability to approximate more accurately the current PA characteristic. These solutions have been compared in terms of complexity and performance w.r.t Error Vector Magnitude (EVM) and Adjacent Channel Leakage Ratio (ACLR). Performance of the proposed approaches are benchmarked with the conventional learning based DPD approach. To offer low-complexity DPD, a dedicated NN structure is designed to derive DPD functions using few neurons. Our numerical simulations demonstrated that our proposed DPDNNWS and meta-learning approaches provide satisfying results when used online for several PA models. Contrary to conventional DPD, these approaches can be used to reduce hardware complexity implementation and data usage during online adaptation. Indeed, through numerical evaluation, it appears that meta-learning can reach satisfying performance using only 3000 IQ symbols during online adaptation. Besides, the DPDNNWS approach exhibits performance close to a linear power amplifier. Both solutions allow to achieve excellent performance compared to the state of the art solutions.

A 24–30-GHz 256-Element Dual-Polarized 5G Phased Array Using Fast On-Chip Beam Calculators and Magnetoelectric Dipole Antennas

We present a 24–30-GHz 256-element dual-polarization transceiver (TRX) phased array based on a 16-element beamformer integrated circuit (BF-IC), 2-element frequency conversion integrated circuit (FC-IC), liquid crystal polymer (LCP)-based combiners and filters, and a tileable package with 64 embedded dual-polarized (dual-pol) antennas. The phased array presented in this work overcomes three key challenges in current 5G millimeter-wave (mmWave) antenna arrays: 1) it supports a dramatic increase in the number of supported fast-access beams; 2) it offers improved power efficiency; and 3) it provides a path to lower solution cost. 1) We enable fast switching among >30000 beams—orders of magnitude improvement over prior work—by employing an on-chip beam calculator in the BF-IC, achieving 200-ns beam setup and 8-ns over-the-air (OTA)-switching time. 2) We enable a module-level transmitter (TX) mode peak power added efficiency (PAE) of 20% using a modular architecture that preserves power amplifier (PA) linearity and efficiency as well as receiver (RX) mode low noise amplifier (LNA) noise figure (NF). The module achieves Psat effective isotropically radiated power (EIRP) of 68.5 dBm and BF-IC NF < 3.9 dB. 3) We lower the solution cost by enabling a wider steering range to reduce the number of phased arrays required in a sectorized coverage scheme, by reducing the IC and package area, and by avoiding calibration. The wider steering range is enabled by using an in-package magnetoelectric dipole antenna (for the first time in silicon-based phased arrays), resulting in steering over ±70° in H- and V-pol in both E- and H-planes without requiring any calibration. Moreover, the module achieves >20-dB cross-polarization isolation across the entire ±70° beam steering range.

A Maximum Efficiency-86% Hybrid Power Modulator for 5G New Radio(NR) Applications

A hybrid power modulator is presented for the radio frequency (RF) power amplifiers of 5th generation mobile communication technology (5G) new radio (NR) applications. A hybrid power modulator utilizing a two-level switching converter and a broadband and high-efficiency linear amplifier is presented. A further improvement in the efficiency of the circuit is achieved by using an optimized supply voltage of the two-level switching converters of 4.5 V. In this way, the overall efficiency is improved by more than 5% compared to using a 5 V supply voltage. The linear amplifier consists of four stages. In order to improve bandwidth and circuit stability, a compensation circuit is added to the linear amplifier that eliminates the poles of the main amplifier by introducing additional zeros, indirectly pushing the pole distribution out of the bandwidth. Using this approach, the linear amplifier achieves a 3-dB bandwidth of 180 MHz and an efficiency of 51%. The hybrid power modulator achieves a maximum output power of 2.4 W and an efficiency of 86% when tracking a 100 MHz 5G-NR signal under a 4 Ω load in a 180 nm CMOS package.

Three-Level Hybrid Envelope Tracking Supply Modulator with High-Bandwidth Wide-Output-Swing

Envelope tracking is a dynamic supply modulation technique, which is mainly used to improve the efficiency of radio frequency power amplifier. For 5G NR mobile devices, this paper presents an envelope tracking supply modulator which is composed of a three-level switching converter and linear amplifier (LA) in parallel. The hysteresis control method is adopted in the supply modulator to improve the bandwidth of the switching converter and the loop response speed. At the same time, a rail-to-rail input-output class AB linear amplifier is designed to achieve a wide output swing and a super source follower is proposed to reduce the output impedance of LA. Designed with the 180 nm CMOS technology, the supply modulator operated at 5G NR 100 MHz envelope signal. The output power of the modulator reaches 1.5 W for a 6 Ω load resistor and the output swing is 4.3 V at 5.0 V supply, and the maximum efficiency reaches 85%.

Gain and noise spectral density in a parametric amplifier with added white noise: Theory and experiment

In this paper, we discuss the behavior of a linear classical parametric amplifier in the presence of white noise and give theoretical estimates of the noise spectral density based on approximate Green’s functions obtained by using averaging techniques. To validate our theory, we compare the analytical results with experimental data from an analog circuit and with numerical simulations of the model’s stochastic differential equations. The experimental data were accurately described by our model. Moreover, we noticed spectral components in the output signal of the amplifier, which are due to noisy precursors of instability. The position, width, and magnitude of these components are in agreement with the noise spectral density obtained by the theory proposed here.

An Energy Recycling Envelope Tracking Supply Modulator Assisted by Small Cap Replica With 89.7% Efficiency and 37% Reduced Linear Amplifier Current for 150 MHz Bandwidth 5G New Radio RF Applications

This article proposes an envelope tracking supply modulator (ETSM) that recycles the originally wasted energy in the linear amplifier (LA) to generate negative voltage <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\mathrm {NEG}}$ </tex-math></inline-formula> and achieve fast down tracking. With the insertion of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\mathrm {NEG}}$ </tex-math></inline-formula> , the negative slope of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$I_{\mathrm {BUCK}}$ </tex-math></inline-formula> becomes 25% larger. <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\mathrm {NEG}}$ </tex-math></inline-formula> is also used to boost the input voltage of buck converter from 2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\mathrm {BAT}}$ </tex-math></inline-formula> to 2.6 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\mathrm {BAT}}$ </tex-math></inline-formula> and raise the positive slope of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$I_{\mathrm {BUCK}}$ </tex-math></inline-formula> by 93%, which improves the transient response of buck converter and decreases <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert I_{\mathrm {LA}}\vert $ </tex-math></inline-formula> by 37%. With energy recycling and high-bandwidth LA replica, ETSM supports 150-MHz 5G new radio (5G NR) application and achieves 89.7% efficiency when output power is 3.7 W. In addition, the proposed differential feedforward technique controls the operation of energy recycling precisely with the calibration logic.

Improving source-in-the-middle continuous-variable quantum key distribution using a heralded hybrid linear amplifier

A hybrid linear amplifier is inserted at the output of the source-in-the-middle distribution protocol to overcome the shortcomings of the transmission distance. The modified protocol aims to maintain a high key rate for long-distance transmission under high noise. It has the potential to significantly broaden the application range of the continuous variable quantum key distribution protocol. The effects of amplifier parameters and noise on the modified protocol are analyzed in detail with regard to applying it to a practical system. To make the simulation more realistic, the effect of finite size on the new protocol is taken into account. It will serve as a guideline for the future use of hybrid linear amplifiers. Different parameters can be adjusted to achieve the best performance for key rates of different quantum channels.

PAPR Reduction of OFDM with DFT Spreading Method

Future communication systems will demand the transmission of huge amounts of data, therefore will require a highly linear power amplifier. The Orthogonal Frequency Division Multiplexing (OFDM) technique is widely used in multimedia services for providing high data rates and providing high Quality of Service. The transmitter power amplifier's range of operation in a communication system is linear. Signal distortion happens when the input signal's amplitude exceeds the linear range of the transmitter power amplifier. Therefore, the transmitter's input signal has to have a low peak to average power ratio (PAPR). The OFDM system has been recognized as the high rate wireless radio channel transmission. Therefore, it will also be highly beneficial for the high-speed communication system. However, due to the extremely high PAPR issue, using the OFDM system in a communication system is not simple. It results in extremely low power efficiency. Therefore, it is crucial to lower the PAPR in the OFDM system in order to employ it in the communication system. By using a discrete Fourier matrix, the Discrete Fourier Transform spreading strategy may significantly lower the PAPR of an OFDM signal. This paper describes the PAPR reduction approach in OFDM signals and examines the effectiveness of OFDM.

The Class D Audio Power Amplifier: A Review

Class D power amplifiers, one of the most critical devices for application in sound systems, face severe challenges due to the increasing requirement of smartphones, digital television, digital sound, and other terminals. The audio power amplifier has developed from a transistor amplifier to a field-effect tube amplifier, and digital amplifiers have made significant progress in circuit technology, components, and ideological understanding. The stumbling blocks for a successful power amplifier are low power efficiency and a high distortion rate. Therefore, Class D audio amplifiers are becoming necessary for smartphones and terminals due to their power efficiency. However, the switching nature and intrinsic worst linearity of Class D amplifiers compared to linear amplifiers make it hard to dominate the market for high-quality speakers. The breakthrough arrived with the GaN device, which is appropriate for fast-switching and high-power-density power electronics switching elements compared with traditional Si devices, thus, reducing power electronic systems’ weight, power consumption, and cost. GaN devices allow Class D audio amplifiers to have high fidelity and efficiency. This paper analyzes and discusses the topological structure and characteristics and makes a judgment that Class D amplifiers based on GaN amplifiers are the future development direction of audio amplifiers.

High-Frequency GaN-Based ANPC Three-Level Converter as a Low-Noise Arbitrary PWL Voltage Generator

Recent advances in the technology of gallium nitride (GaN) power devices and high-frequency magnetic materials are key enablers of small, compact designs of power electronic converters in the megahertz range and the power range up to several hundreds of watts. However, impact of different switch modulation strategies along with the devices and magnetic materials must be carefully characterized to fully understand the boundaries of current technology and to be able to exploit it fully. This is usually performed through a holistic, automated design procedure based on multiobjective optimization which focuses on the converter efficiency and power density for the given electrical parameters. In this article, an optimized 100-W, 1.75-MHz switching frequency, four-quadrant, piecewise linear (PWL) arbitrary voltage generator based on active neutral-point-clamped (ANPC) three-level converter is presented. Diversity of modulation techniques for the hard-switched ANPC converter suitable for high-frequency (HF) applications are revisited, and impact on switching losses is characterized in detail. The generator is capable of providing <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm {\mathrm {100}}~\text {V}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm {\mathrm {1}}~\text {A}$ </tex-math></inline-formula> at the output, with tracking speeds up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2~\text {V/}\mu \text {s}$ </tex-math></inline-formula> and steady-state efficiency above 95% with a physical size less than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$12~\text {cm}^{2}$ </tex-math></inline-formula> . Thermal management of the system is successfully resolved using advanced cooling plates based on pyrolytic graphite sheets (PGSs) and forced air convection. Having these characteristics, the presented generator outperforms the existing linear and hybrid power amplifiers (LPA/HPA) from the literature.