5 W monolithic HBT amplifier for broadband X-band applications

Abstract

The first monolithic heterojunction bipolar transistor (HBT) amplifier producing greater than 5-W output power at X-band frequencies is reported. Monolithic impedance-matching circuits were designed using measured and modeled large-signal device parameters at the unit-cell level. Unit cells were then connected in parallel to obtain an output-power increase proportional to unit-cell count. A single-stage, totally monolithic amplifier was fabricated using 2.4-mm-emitter-length AlGaAs-GaAs HBT for operation in the 7-10-GHz frequency range. A maximum of 5.3-W CW output power was obtained in this frequency range with 4.6-dB gain and 22% power-added efficiency.<>