A study of SiGe signal sources in the 220–330 GHz range

This paper investigates fundamental and push-push SiGe HBT voltage-controlled-oscillator topologies with and without doublers, as possible solutions for efficient milliwatt-level, low-noise signal sources at sub-millimeter wave frequencies. A fundamental frequency Colpitts VCO covers the 218-246 GHz range (the highest for SiGe HBTs) with up to -3.6 dBm output power and 0.8% efficiency. A Colpitts-Clapp VCO-doubler shows -1.7 dBm output power around 290 GHz, a record -101 dBc/Hz phase noise at 10 MHz offset, 7.5% tuning range and 0.4% efficiency. These efficiency numbers are 2-4 times higher than those of recently reported 300-GHz SiGe or CMOS sources based on multipliers or free-space power combining.