Time-domain optical sampling of nonlinear microwave amplifiers

Time domain measurements of the output waveforms of two 8-GHz high-efficiency power amplifiers are presented. A new photoconductive probe has enabled nonintrusive absolute voltage measurements which confirm switched-mode class-E and F operation. In order to analyze nonlinear amplifiers designed to deliver a sinusoidal wave to the load, voltages at characteristic points inside the circuit need to be known. The high-impedance probe used here is an optoelectronic sampler which can sense the charge on an exposed interconnect or the field associated with a buried interconnect. This field data is then converted into voltage.