Broadband and Efficient Envelope Amplifier for Envelope Elimination and Restoration/Envelope Tracking Higher-Efficiency Power Amplifiers

Abstract

Increasing the efficiency of transmitters, as the largest consumers of energy, is relevant for any wireless communication devices. For higher efficiency, a number of methods are used, including envelope tracking and envelope elimination and restoration. Increasing the bandwidth of used frequencies requires expanding envelope modulators bandwidth up to 250–500 MHz or more. The possibility of using amplifiers with input signal quantization (AISQ), as an alternative to the most common hybrid envelope tracking modulators, is considered. An approach has been developed for optimizing AISQ characteristics according to the criterion of minimum loss when amplifying modern telecommunication signals with Rayleigh envelope distribution. The optimal quantization levels are determined and the energy characteristics of AISQ are calculated. AISQ loss power is shown to decrease by 1.66 times with two-level quantization, by 2.4 times with three-level quantization, and by a factor of 3.0–3.7 for four–five quantization levels compared to a class B amplifier. With these parameters, AISQ becomes competitive with respect to hybrid envelope tracking modulators but does not have electromagnetic interference from the pulse width modulation (PWM) path.

High-Efficiency GaN-Based Power Amplifiers for Envelope Nonlinearities’ Mitigation in VHF Wideband Polar-Mode Transmitters

“…The WLEA presents good stability in frequency and draws good linearity figu However, polar transmission techniques are supposed to improve the power efficienc conventional RF PAs, and a linear amplifier may not be competitive to provide an provement in these terms. To improve the efficiency of high-dynamic-performance lin regulators, several solutions (most of them based on a series combination because para topologies usually require a push-pull linear PA) have already been proposed for m years (slow ET, multilevel-based supply class-G PAs), and the common idea of all of th is usually to use a power supply that, in combination with the WLEA, is able to provid variable voltage that tracks the amplified waveform [34][35][36][37][38]. As the WLEA is respons for dynamic performance and linearity, the voltage tracking power supply does not h such stringent linearity and voltage ripple requirements, making it easy to implement conventional high-efficiency power conversion methods can be easily applied.…”