A Ka-band GaInP/GaAs HBT double balanced upconvert mixer

A Ka-band GaInP/GaAs HBT double balanced upconvert mixer has been designed and fabricated. This circuit is to be used in a multifunction T/R module for local multipoint distribution systems (LMDS) which include both analog and digital transmission. A conversion gain of 1 dB, and an output power of -10 dBm from 27 to 30 GHz for an LO input power of 10 dBm at 26 GHz were measured. The LO isolation to the output was measured to be 20 dB. These results are the best reported at Ka-band for a mixer using transistors from a digital HBT library.