AM/PM Characterization of Wideband Power Amplifiers

Abstract

This paper presents the linearity assessment of two state-of-the-art wideband power amplifiers, a single stage class AB and a two-way 6 dB Doherty, in terms of amplitude-to-phase-modulation (AM/PM) distortion. The simulated and measured characteristics are shown and discussed. The class AB amplifier maintains AM/PM within 6 • from 1 to 4 GHz, i.e. on a 120% bandwidth, while the Doherty amplifier has similar performance from 2.2 to 2.9 GHz, i.e. on a 28% bandwidth. This characterization campaign highlights the superior linearity of the class AB amplifier over relative bandwidths that exceed 100% but, at the same time, the potential of the Doherty amplifier to maintain very limited (within 10 • ) amplitude-to-phase-modulation distortion over bandwidths up to around 60%. Both power amplifiers are well in line with the state of the art also in terms of linearity, besides output power, gain, and efficiency performance.

AM/AM and AM/PM Characterization of a GaN Phase and Amplitude Setting Circuit

“…Furthermore, the availability of multifunctional monolithic microwave integrated circuits (MMICs) allowed the Active Electronically Scanned Array (AESA) System to present a technological breakthrough in improved reliability, reconfigurability, performance, wideband capabilities, and ease of installation in space communication systems [26]. To follow technological advancements, thorough characterization of RF front ends is required, as the front end always operates at higher frequencies, owing to the ever-growing demand for spectrally efficient wireless communication chips [27][28][29][30]. In addition to measuring the linear response, achieved through scattering parameters (S-parameters), it is also important to characterize the performance of the signal conditioning circuits in terms of non-linear figures of merit, such as the amplitude-to-amplitude (AM/AM) conversion and the amplitude-to-phase (AM/PM) conversion characteristics.…”