Novel Large Signal S-Parameter Measurement Technique Aids GaAs Power Amplifier Design

This paper describes a method for obtaining the microstrip circuit source and load impedances which permit a certain transistor gain/power load performance to be realised. A conventional power test bench, a small signal network analyser and a simple computer program are used, and the method may be extended to give complete large-signal S-parameter characterisation of the transistor for any desired power output, by a series of 4 small-signal S-parameter measurements and one large-signal measurement. The validity of the measurements made is proven by using them to design a 5.9-6.4 GHz balanced amplifier giving IW of output power with 20 dB gain at 1 dB gain compression point.