A K-band SiGe bipolar VCO with transformer-coupled varactor for backhaul links

Abstract

A K-band SiGe bipolar VCO with a transformer-coupled varactor operating from 18.1 to 20.5 GHz is presented. The oscillator features a phase noise as low as -135.7 dBc/Hz at 10 MHz offset from the 19.5 GHz carrier while drawing 7 rnA from the 3.3 V supply. The VCO shows a state-of-the-art FOM of -188 dBc/Hz and an excellent FOMT of -191 dBc/Hz. The oscillator is tailored to the communication systems operating in the lower portion of the E-band. It is intended to be followed by a frequency multiplier by four, reported elsewhere.