Measurements of time-domain voltage/current waveforms at RF and microwave frequencies based on the use of a vector network analyzer for the characterization of nonlinear devices - Application to high-efficiency power amplifiers and frequency-multipliers optimization

A new time-domain waveform measurement system based on the combination of a n harmonic source and load-pull setup with a modified vector network analyz er (VNA) is presented. It allows the visualization, the measurement, and th e optimization of high-frequency currents and voltages at both ports of non linear microwave devices. Measurements of GaAs field effect transistor (FET 's) and GaInP/GaAs heterojunction bipolar transistor (HBT's) at L-band were performed to demonstrate the great capabilities of the system, On one hand , voltage and current waveforms at both ports of transistors, working as po wer amplifiers, were optimized for maximum power-added efficiency. On the o ther hand, time-domain waveforms of transistors operating as frequency mult ipliers were optimized for maximum conversion gain. Such results prove the capabilities offered by this new nonlinear time-domain measurement system t o aid in designing optimized power amplifiers or frequency multipliers, The y also provide valuable information for nonlinear transistor model validati on.