Power optimization of high-efficiency microwave MESFET oscillators

Achieving high output power and efficiency in GaAs MESFET oscillators is ma inly hampered by the device's parasitics, its static I-V characteristics, a nd the circuit embedding impedance. In this paper, the derivation of the re lationship between oscillator output power and various circuit and device p arameters is presented. From these analytical expressions, optimum operatin g conditions for maximum oscillator output power and efficiency are determi ned, The analysis method employed here is based upon a quasi-linear approac h and an open-loop model of the oscillator. The design procedure is verifie d by measurements on an experimental circuit, which have demonstrated a dc/ radio-frequency conversion efficiency of 54%.