Monolithic 26 GHz and 40 GHz VCOs with SiGe heterojunction bipolar transistor

Monolithically integrated 26 GHz and 40 GHz VCOs have been built with SiGe heterojunction bipolar transistors (HBT). The tuning range was more than 3 GHz, the output power behind an on-chip 10 dB-attenuator reached -13 dBm. The HBTs and the varactors were fabricated on the same high-resistivity substrate using the same MBE-grown layers. The transistors had an f/sub max/ of about 60 GHz and were operated in common-emitter series feedback configuration. Chip sizes including the microstrip resonators were 2/spl times/2.8 mm/sup 2/.