33-GHz monolithic cascode AlInAs/GaInAs heterojunction bipolar transistor feedback amplifier

Microwave cascode feedback amplifiers with 8.6-dB gain and DC to 33-GHz bandwidth were developed. The amplifiers utilize AlIn-As/GaInAs heterojunction bipolar transistors having f/sub max/=70 GHz and f/sub tau /=90 GHz. Because of the significant collector-base feedback time constant the cascode configuration provides a large improvement in amplifier bandwidth, but a low-impedance bias node must be provided for the common-base transistor. An active bias network was thus used which eliminates the need for on-wafer Si/sub 3/N/sub 4/ bypass capacitors.>