A 7.4 to 8.4 GHz high efficiency PHEMT three-stage power amplifier

Abstract

This paper describes the design, fabrication, and performance of a 7.4 GHz to 8.4 GHz 3-stage PHEMT power amplifier. To the best of our knowledge, this amplifier has achieved the highest efficiency, power, and gain ever for a three-stage power amplifier at X Band.At a drain voltage of 6 volts, measured power added efficiency was between 50 YO to 60 YO with a CW power output of 35 dBm and an associated gain of 24 dB. The amplifier was stable over all measured biases and all drive levels.

On linearisation of microwave-transmitter solid-state power amplifiers

“…Where it peaks in this nonlinear region varies from device to device and, of course, is dependent on the amplifier class. However, the peak value of PAE, and even the significant PAE improvements available, are usually beyond the PA's 1-dB compression point (P1dB) (see, for example, [2][3][4][5][6]). Achieving linear operation by operating point backoff will thus be at the expense of PAE.…”

“…A Volterra series analysis was carried out, which considered the contributions of all nonlinearities in the amplifier stage and the main nonlinearity in the diode predistorter. Currents associated with the base-charging capacitance and the collector current have been shown to be the most significant contributions to IM 3 . In so far as these two currents directly depend on baseemitter diode nonlinearity, the linearisation of the transistor's base-emitter diode characteristic provides a lower IM 3 .…”

“…Currents associated with the base-charging capacitance and the collector current have been shown to be the most significant contributions to IM 3 . In so far as these two currents directly depend on baseemitter diode nonlinearity, the linearisation of the transistor's base-emitter diode characteristic provides a lower IM 3 . A closed-form expression for IM 3 arising from the composite diode predistorter and amplifier was obtained [27].…”

“…In so far as these two currents directly depend on baseemitter diode nonlinearity, the linearisation of the transistor's base-emitter diode characteristic provides a lower IM 3 . A closed-form expression for IM 3 arising from the composite diode predistorter and amplifier was obtained [27]. Noting that adding two i-v exponential characteristics in series, results in a softened overall i-v transfer function intuitively explains how the series diode lineariser connected at the base of the bipolar stage serves to linearise the overall base diode, thus reducing the signal distortion at the amplifier output.…”

A fully matched 9 W compact PHEMT MMIC high power amplifier for X‐band phase array radar applications

“…Previously, amplifiers with high power-added efficiency and high output power have been demonstrated [2][3][4][5]. However, the output power was not high enough for phase array radars.…”