A DC to 194-GHz Distributed Mixer in 250-nm InP DHBT Technology

A distributed mixer was designed and fabricated in 250-nm indium phosphide (InP) double-heterojunction bipolar transistor (DHBT) technology for 200-GHz bandwidth digital-to-analog converters. A method using non-uniform emitter resistors in the mixer unit cells is proposed to compensate for degradation of conversion gain (CG). The fabricated mixer achieves a bandwidth of 194 GHz from DC to 194 GHz with a CG of -3 dB, which is the widest bandwidth ever reported to the best of the authors' knowledge.