Quantifying Trade-offs in Power-Amplifier Linearity, Spectral and Power Efficiency

In this paper, we present a systematic analysis of how concurrent signals within a specified frequency band affect the linearity and spectral efficiency of a high-efficiency power amplifier (PA). Using a large-signal measurement setup with a wide instantaneous bandwidth, a PA is characterized with 1 to 8 multi-carrier signals, each with a 10MHz bandwidth. The signals are evenly spaced within a 500MHz band centered around 4.35 GHz. The single-stage hybrid PA is designed with a GaN-on-SiC packaged device with CW output power above 10W from 4 to 5 GHz. In the design band from 4.1-4.6 GHz, the PAE exceeds 50% with a saturated gain above 8 dB at 28V drain bias, agreeing well with nonlinear simulations. The efficiency, output power, noise power ratio, and spectral efficiency are quantified in measurement and show that the overall performance can be appropriately defined by an equally weighted figure of merit which is a function of the number of signals.