A wideband differential VCO based on double-short-path loop architecture

A new voltage controlled oscillator (VCO) design based on a ring oscillator with a double-short-path loop architecture is presented. The proposed circuit employs the Gilbert cell as a delay component and two short paths in order to expand the oscillation frequency tuning range. We designed and fabricated the six-stage ring VCO with double-short-path architecture in 0.18-μm CMOS technology. It has about 150 % wider tuning range than the conventional one and can oscillate from 0.36 to 1.2 GHz.