A 246 GHz fundamental source with a peak output power of 2.8 dBm

A 246 GHz source for imaging and incoherent high data rate communication applications is presented. The source consists of a fundamental free-running Colpitts oscillator cascaded with a differential common base (CB) buffer stage and a 3-stage power amplifier (PA). The circuit has been fabricated in a 130 nm SiGe HBT technology with f_T/f_max of 300/500 GHz. At 246 GHz, the measured output power is 2.8 dBm and the overall DC to RF conversion efficiency is 0.43%. The available output power from the oscillator alone is -4.2 dBm (after correcting for the PA gain of 10 dB and another 3 dB loss due to output pad and balun at 246 GHz).