A 1.9-GHz Si bipolar quadrature VCO with fully-integrated LC tank

A fully monolithic voltage controlled oscillator with quadrature outputs has been implemented in a Si bipolar process with a cut-off frequency of 40 GHz. The circuit techniques to achieve highly accurate quadrature outputs as well as the low phase noise with low power dissipation are used. The phase and gain errors are less than 1 degree and 0.1 dB, respectively. The measured phase noise at a 600 kHz offset frequency from a 1.9 GHz center frequency is -123 dBc/Hz. The quadrature cores drain 16 mA from 2.7 V supply.