High-performance differential VCO based on Armstrong oscillator topology

A symmetric topology based on the classical Armstrong's oscillator was developed and implemented as a fully monolithic voltage-controlled oscillator using ST Microelectronics' 0.35-/spl mu/m BICMOS process (f/sub T/=35 GHz). It oscillates at a center frequency of 4.4 GHz, has a tuning range of 1.0 GHz, delivers a single-ended output power of -6.5 dBm, and the minimum current consumption is less than 4 mA from a 2.5-V power supply. The phase noise is -125 dBc/Hz, measured at 3-MHz offset.