High-performance differential VCO based on Armstrong oscillator topology

A symmetric topology based on the classical Armstrong's oscillator was deve loped and implemented as a fully monolithic voltage-controlled oscillator u sing ST Microelectronics' 0.35-mum BiCMOS process (f(T) = 35 GHz), It oscil lates at a center frequency of 4.4 GHz, has a tuning range of 1.0 GHz, deli vers a single-ended output power of -6.5 dBm, and the minimum current consu mption is less than 4 mA from a 2.5-V power supply. The phase noise is -125 dBc/Hz, measured at 3-MHz offset.