This paper presents an envelope tracking (ET) transmitter architecture based on the combination of a novel 3-bit (N = 3) supply modulator and digital predistortion (DPD). The proposed power converter is direct digital-to-analog conversion that implements binary-coded sum N isolated dc voltages, allowing synthesis output waveform with L 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</sup> voltage levels, binary distribution in range ΔV VM -...

GaN power switches provide remarkable performance in terms of power-density, reduced parasitics, and high-thermal handling capability that enable the realization very efficient compact dc/dc converters. Despite exhibiting state-of-the-art channel conductivity, high electron mobility transistor (HEMT) devices are affected by degradation dynamic ON-Resistance (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> ) at increasing OFF-state...

This paper demonstrates a high-efficiency dualband RF power amplifier (PA) for sub-6 GHz 5G carrier aggregation. The dual-band PA is tested with modulated signals generated by new algorithm designed to provide realistic waveforms aggregation scenarios, allowing flexible complex (IQ) sequences arbitrary peak-to-average ratio (PAPR), bandwidth, and band distribution. A single-stage packaged 6-W transistor diplexer-like output matching network that separates the two bands into outputs. It...

This paper presents a broadband efficient power amplifier (PA) targeting sub-6-GHz 5G base station applications. Due to the demanding requirements in both peak-to-average ratio (PAPR) and bandwidth systems, we employ combination of load supply modulation for efficiency enhancement. Active matching, implemented using an RF-input load-modulated balanced (LMBA) architecture, enables octave-bandwidth operation. Supply modulation, which is carrier frequency agnostic, then used further extend...

The asymmetry between capture and release time constants associated with charge-trapping phenomena observed in the electrical characteristics of microwave gallium-nitride (GaN) field-effect transistors (FETs) introduces distortion GaN-based power amplifiers (PA). PAs that operate supply modulation to increase efficiency are particularly affected by this phenomenon, since GaN FET trap state exhibits a nonlinear dependence on voltage applied device terminals. In paper, measurement approach...

This paper presents a dynamic characterization of multilevel (ML) Chireix outphasing (ML-CO) power amplifier (PA) with modulated signals. The ML-CO technique combines the advantages envelope tracking and architectures by limiting supply modulation to discrete levels an efficient power-DAC modulator using for fine amplitude control. We describe experimental test bench that supplies required phase- time-aligned signals simultaneously. Pulsed is used design ML memoryless polynomial DPD....

In this paper, we present a high-efficiency transmitter based on an integrated circuit (IC) supply modulator implemented in the same 0.15-μm gallium nitride (GaN)-on-SiC RF process as power amplifier (PA) monolithic microwave IC. The X-band 10-W two-stage PA is designed for stable operation with minimal drain capacitance, which enables fast modulation. multilevel provides eight voltage levels 3-bit digital control [(power digital-to-analog converter (pDAC)], achieving state-of-the-art slew...

This article presents a design methodology for an asymmetrical Doherty Power Amplifier (DPA) which achieves high average efficiency at back off across its operating bandwidth. It is shown that by combining continuous modes with post matching techniques, it possible to achieve excellent performance whilst maintaining broadband operation. Analysis provided on how the knee effect can reduce effective potential of Class J and Continuous Inverse F modes. An optimum combination <inline-formula...

This paper investigates the output power and efficiency improvements in a K-band amplifier (PA) that can be achieved using analog pre-distortion (APD). At first, APD tuning voltage is optimized to maximize gain phase flatness Gaussian pulses. Next, PA average swept noise-power ratio (NPR) of 750 MHz signal measured with enabled disabled. It found improves between 1 W 1.6 (or +2 dB) for NPRs 16 29 dB. same time, by 7 percentage points (pp) this 31 % peak-efficiency PA. These results suggest...

The demand for linear and highly efficient RF amplifiers has continued to rise without showing signs of stopping, as the world looks implementation 5G. Modern communication signals gave demand, desire efficiently utilize limited electromagnetic spectrum led widespread use amplitude- phase-modulated signals, e.g., LTE Advanced, that carrier aggregation achieve broader bandwidths. defense industry may provide even more applications, electronic warfare techniques make multitone sometimes...

In this paper, a novel unsupervised machine learning (ML) algorithm is presented for the expeditious RF fingerprinting of LoRa modulated chirps. Identification based on received signal strength indicator (RSSI) alone unlikely to yield robust means sensor authentication within critical infrastructure deployment. Here, an ML used rapidly train artificial neural network (ANN) matrix creating self-organizing maps (SOMs) each authentic transmitter and potential rogue node. A general classifier...

This work presents multi-level supply modulation of a load modulated balanced amplifier (LMBA). The RF-input LMBA employs dynamic active matching for efficient operation over an octave bandwidth. Supply is natural candidate to further enhance the back-off efficiency this broadband due its independence on RF carrier frequency. In ET-LMBA prototype demonstrated here, hybrid converter (power DAC) produces levels from 10 30 V modulate drain amplifier. Digital predistortion used linearize...

This paper presents a supply modulated X-band 12-W peak power transmitter that maintains an average efficiency greater than 50% for various shapes of amplitude-modulated pulses. The main amplifier is two-stage GaN-on-SiC MMIC with 65%, while the pulse envelope modulator 95% efficient hybrid 3-b DAC implemented GaN-on-Si transistor switches. Envelope shaping pulsed waveform results in improved spectral confinement 15 dB first sideband compared constant-envelope pulses, over 20 points...

In this work, a digital predistortion (DPD) model for the linearization of RF power amplifiers (PAs) is presented. The provides linearized gain (DPD + PA) independent instantaneous transistor channel temperature within predefined window. Channel variations due to varying ambient temperatures or changes in signal probability density function (PDF) cause long-term memory effects, which results dispersed (dynamic) AM/AM and AM/PM characteristics. presented used compensate effects self-heating...

We present a diplexed power amplifier (PA) architecture for achieving more than octave bandwidth with high efficiency. Two relatively narrowband single-stage PAs are connected contiguous diplexer-combiner network. The average efficiency across the larger band is maintained flat gain response from 1.8 to 4 GHz. To maintain efficiency, two transistors biased in class B. One of paths turned on each subband, and transition region, combine. In both element amplifiers, 7-W Qorvo GaN packaged...

In this letter, we present a design of fast gate-switching power amplifier (GSPA) aimed at reducing its consumption. This GSPA features dedicated circuit that commutates the gallium nitride (GaN) transistor between nominal gate bias voltage (GSPA ON) and strong negative OFF), thereby generating two discrete output levels in an RF-pulsewidth modulation (PWM) fashion. A circuit, including commercial digital isolator, is designed to switch voltages. The stability resistor transmission line (TL)...

A pulsed characterization of gallium nitride (GaN) high-electron mobility transistors (HEMTs) under a controlled trap and thermal state is performed to evaluate the trapping-induced degradation in actual operating conditions, corresponding different classes power amplifiers (PAs). Two state-of-the-art GaN-on-SiC technologies are evaluated: 0.15-μm Qorvo 0.25-μm Wolfspeed HEMTs, with examples relative class-AB, class-E, supply modulated operation. It shown that, order get an accurate device...

This paper presents a study of supply modulation Doherty power amplifier (DPA) designed for linear operation. The symmetrical DPA is with Wolfspeed 6-W packaged devices operation at 3.5 GHz peak output 42dBm and power-added efficiency (PAE) 55%. Supply characterized statically when the main auxiliary voltages are modulated separately, as well simultaneously. then 60-MHz LTE-like signals 6 dB 10 peak-to-average ratios (PAPR). After digital pre-distortion using an iterative learning control...

This paper presents the characterization of a multi-level Chireix outphasing PA with GaN discrete supply modulator MMIC at 9.7GHz. The internal PAs include class-F harmonic terminations, while combiner determines fundamental frequency load modulation. A power-DAC architecture provides 8 levels 3 half-bridges, maintaining more than 85% efficiency. combination two achieves peak output power 4.8W, and average total efficiencies for 6dB PAR QPSK signal 44.1% 48.1% without considering...

This work presents a dynamic characterization of multi-level Chireix outphasing (ML-CO) power amplifier (PA) with modulated signals. The ML-CO technique combines the advantages envelope tracking and architectures by limiting supply modulation to discrete levels (enabled an efficient DAC modulator) using for fine amplitude control. We describe development experimental test bench able phase- time-aligned signals simultaneously. Pulse is used design multilevel memory-less polynomial DPD....

This work presents a new RF power amplifier characterization technique based on Gaussian pulse, which is shown to approximate the envelope of multicarrier signal with 0.5% error around peaks. The standard deviation pulses inversely proportional I/Q bandwidth. test accurately capture nonlinear memory effects that result in gain dispersion after peak reached. As an example, it amplitude and phase can vary up 2.3 dB 6° for 10-W 3.75-GHz GaN power-amplifier evaluation board, depending bandwidth level.

This paper presents an analysis of a 8-12 GHz active 0.25 μm GaAs pHEMT MMIC circulator intended for integration into phased array. The architecture is based on closed-loop connection three asymmetric -5.6-dB Lange couplers and resistive-feedback gain-matched amplifiers. nominal simulated performance shows isolation 20 dB over 40% bandwidth, with return loss better than 10 insertion gain 2.4 across the band. degradation in circuit analyzed as function variations port impedance. A loop-gain...

This paper explores the use of waveform engineered continuous modes with aim achieving a broadband Radio Frequency Power Amplifier (RF PA) high average efficiency across its operating bandwidth. The effect High Electron Mobility Transistors (HEMTs) knee voltage can have on achievable drain Class J and Continuous Inverse F (CCF <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> ) is presented. Drain be as low 60% for 82% CCF when...

This work presents the design, characterization, and validation of an Analog Pre-Distortion (APD) circuit. circuit is based on a dual-branch configuration with Schottky diode as non-linear element delay line. The first experimentally characterized large signal model extracted. manufactured APD provides 6 GHz bandwidth around central frequency 18 GHz. At large-signal, this shows to be able correct up 3 dB HPA compression 9° phase rotation within large-signal bandwidth, low insertion loss only...