Karun Rawat

This work presents a nonlinear embedding model approach for designing continuous class E (CCE) power amplifiers (PAs) based on gallium nitride (GaN)-HEMT packaged devices with harmonics above 6 GHz. This approach extends the embedding model for broadband PAs by enabling direct access to the current generator plane (CP), as well as the accurate projection of loads at the package plane (PP). By exploiting the embedding model’s ability to enforce Foster behavior at PP, this method circumvents non-Foster load challenges and simplifies the design of wideband passive matching networks. CCE design parameter ( $\phi $ ) possibility is investigated over the operating frequency range to achieve the wideband Foster behavior. For validation, two CCE PA designs with CGHV1F025S (plastic DFN) and CGH40025F (ceramic) devices are implemented using the advancements in the extracted embedding model. These PAs deliver 43–44.5 dBm of output power and 51.3%–69.1% drain efficiency (DE) in the S-band. This work provides comprehensive, systematic guidelines for parameter extraction, and the results establish embedding model-assisted CCE design as a scalable solution for high-efficiency broadband RF transmitters.

This article presents the design of a continuous class F (CCF) power amplifier (PA) on a gallium nitride-based monolithic microwave integrated circuit (MMIC) technology. In general, the design equations of the conventional CCF PA consider a linear drain-to-source capacitance ( $C_{ds}$ ). The present work exploits the nonlinear variation of $C_{ds}$ in GaN MMIC devices to achieve effective active harmonic injection. The design equations of the conventional CCF mode are modified by considering the varactor effect of the $C_{ds}$ . A detailed analysis has been carried out to understand the nature of these loads and their impact on the enhancement of efficiency of the CCF PA modes.

This work presents a new design space of Extended continuous class-F (ECCF) power amplifiers with resistive second harmonic impedance after including the effect of non-linear drain-to-source capacitance $C_{\mathbf {ds}}~_{\mathbf {}}$ of a transistor. The expression of current waveforms is modified to include the impact of nonlinear drain to source capacitance in this mode. The analysis shows that this non-linear capacitance generates harmonic current, which alters the load trajectory on the Smith chart by achieving active and modified passive second harmonic loads. These active harmonic loads at the current reference plane of the transistor represent an active harmonic injection that increases the drain efficiency. Consequently, a design methodology is proposed to obtain passive loads for matching that ensures this active harmonic injection at the current reference plane of the transistor provides an efficiency improvement in the ECCF mode while maintaining the operation more than the octave frequency range. The proposed theory is validated by designing a power amplifier operating from 0.8-3.0 GHz (115.7% fractional bandwidth) with a measured drain efficiency of 57.24-70.3%, and an output power of 41.7-44.63 dBm. The power amplifier is also tested with modulated signals and linearized using digital predistortion to qualify spectral mask with a measured (Error Vector Magnitude) EVM of 1.54%.

This article presents the design and implementation of a novel hybrid distributed power amplifier (HDPA) using 0.25- $\mu $ m gallium nitride (GaN) monolithic microwave integrated circuit (MMIC) technology. The proposed HDPA integrates the benefits of both uniform and nonuniform distributed power amplifiers (NDPAs) to enhance the gain–bandwidth product and efficiency from 4 to 19.5 GHz, covering the C-Ku band. Performance evaluations indicate an output power range of 36.5–41.5 dBm, power-added efficiency (PAE) of 10.2%–20.9%, and large-signal gain of 16.5–21.5 dB. Additionally, the fabricated prototype was encapsulated in a quad-flat no-lead (QFN) package and tested, yielding an output power of 36–39.6 dBm, a gain of 16–19.6 dB, and 10.7% average PAE. The proposed HDPA offers an optimal impedance profile for better power-combining efficiency, making it suitable for broadband RF applications, such as radar and satellite communications.

A fully integrated millimeter-wave power amplifier has been designed and fabricated using a 0.13 μm SiGe BiCMOS process technology. The design is based on extracting device parasitics and utilizing them in a matching network based on a bandpass topology. This design technique assisted in attaining a wideband performance without using any on-chip inductors or transformers. The amplifier operates over the Ka & V -band ranging from 36 GHz to 53 GHz with a peak saturated power of 17.7 dBm, peak power added efficiency (PAE) of 20.5% and a gain of 19.7 dB at 46 GHz. The performance is also validated with wideband 5G signals of 50 MHz and 100 MHz channel bandwidth using 64-QAM in n262 5G NR FR2 bands (47.2 GHz–48.2 GHz). The digital predistortion is used to linearize the PA in order to qualify the required spectral mask with an error vector magnitude of 2.2%. The proposed design is compact and occupies a chip area of 1.11 mm ² , including the pads.

This paper presents the design of a Ku band GaN MMIC power amplifier (PA) using UMS 0.25μm GaN MMIC technology. The Nonlinear output capacitance (Cout) of the GaN HEMT is used to improve the efficiency of the PA. The design equations of the continuous class F-1 (CCF-1) mode are redefined to present active second harmonic loads. It is noted that the efficiency of PA improves with active second harmonic loads compared to conventional CCF-1 mode, where loads are purely reactive. In CCF-1 mode with active second harmonic load, the peak of the current waveform increases to show half-sinusoidal characteristics and improves the output power and efficiency of the PA. An analysis is presented to investigate the impact of nonlinear Cout on the performance of the GaN MMIC PA. The nonlinear Cout can present an active second harmonic load at the current source reference plane (CRP), even with a passive matching network at the extrinsic reference plane (ERP). The proposed theory is validated by designing a PA operating from 16.5 to 17.4 GHz. The chip size of the two-stage GaN MMIC PA is 3mm×5mm. The Ku band GaN MMIC PA has achieved the power-added efficiency (PAE) of 15.7 to 26% with an output power of 36.7 to 38.9 dBm. The gain at saturation varied from 9.7-14.3 dB. The input and output reflection coefficients of the implemented PA are less than -6.5 dB and -10 dB, respectively.

This article describes a wideband filter-less radio frequency (RF) power amplifier (PA) with in-band harmonics suppression using a polyphase network. The novel passive polyphase (three-way three-phase) network helps in suppressing both the second and third harmonics of the PA present within the operating band. The architecture uses three extended continuous class F (CCF) PAs, which are combined using the proposed polyphase network. The output power of the overall system varies between 41.7 and 42.4 dBm from 0.65 to 2.05 GHz. The second and third harmonic suppression levels are improved by 15–28 and 12–15 dB, respectively, when compared with that of the standalone PA.

In modern wireless compact transmitters, Power Amplifier (PA) behavior is considerably affected by the impedance mismatch between the PA’s output and the antenna’s input. This PA’s output mismatch results in a reflection at the PA–antenna interface. In this brief, reflection-aware PA modeling and digital predistortion (DPD) techniques are proposed to mitigate the negative impact of this mismatch on the forward and reverse models of the PA. An Augmented Convolutional neural network model $(\boldsymbol{\Gamma }$ ACNN) is proposed to linearize a Doherty PA under different values of the output mismatch using a single set of coefficients. The developed DPD shows robust performance metrics like normalized mean square error (NMSE), and adjacent channel power ratio (ACPR) under diverse complex output mismatch levels.

This paper presents a new extended continuum of class E (ECCE) mode for multi-octave power amplifier (PA) design. The impedance space of class E mode is expanded by considering the resistive component in the second harmonic impedance. This provides an overlap between the fundamental and second harmonic loads, which is for the first time explored for class E mode, enabling its design beyond the octave band. This mode offers a wide impedance range for the third harmonic termination, unlike a fixed point (open/short) in other extended continuous modes. This wide third harmonic design space provides high flexibility to design output matching. To verify the validity of the proposed mode, a PA has been designed using a 10W GaN HEMT CGH40010F from Wolfspeed. A design scheme is also presented to obtain the feasible matching loads at desired frequencies. The PA operates over a multi-octave band from 0.45 -2.9 GHz, corresponding to the fractional bandwidth of 146.27%. This circuit provides drain efficiency of 60-72.9% and the output power between 39.6-41.7 dBm over the operating band.

Currently, the wireless communication industry is experiencing rapid advances in the smooth migration and upgrading of technology. Because of this, communication systems operating in multiple frequency bands are of interest, and multiband circuits play an important role in the design of compact and low-cost multiband communication systems. A multiband multimode communication system based on software-defined radio (SDR) is shown in Figure 1 . In this communication system, the multiband capability is primarily achieved by the hardware, (i.e., using multiband microwave circuits) [1] . Passive microwave circuits are essential to the design of any communication system; for example, quadrature branch line couplers (BLCs) are used in array beamforming circuit designs [2] , while Wilkinson power dividers (WPDs) [3] , baluns [4] , and out-of-phase power dividers [5] play a vital role in designing balanced/unbalanced circuits.