High power density pulsed X-band heterojunction bipolar transistors

Abrupt junction Npn AlGaAs/GaAs heterojunction bipolar transistors giving 10GHz output power density of 6.2mW/μm2 (18.7W per mm emitter length) are reported. Pulse length was 300nS with 33% duty cycle. Associated gain and power-added efficiency were 5.0dB and 46%, respectively. Associated peak power was 561mW. Peak and average powers were measured as a function of pulse length at fixed duty cycle and found to increase sharply from CW values for pulse lengths less than 1000nS.