Effect of thermal impedance on chirp characteristics of high-efficiency pulsed InP oscillators

Measurements have been made of the chirp characteristics of high-efficiency pulsed InP oscillators at 17 GHz for a variety of device constructions. The magnitude of the chirp follows reasonably closely the transient changes in active-layer temperature with the same sign as the inherent device dF/dT. Using an integral heatsink construction, chirp levels of less than 15 MHz/¿s have been achieved at 17 GHz with peak powers of 9 W and 14.5% efficiency.