A fully-integrated low-power low-noise 2.6-GHz bipolar VCO for wireless applications

The low quality factor of the inductors fabricated in fully-integrated LC tanks results in a poor indirect stability of the oscillators, which are therefore highly sensitive to low-frequency noise and disturbances coupled through substrate and supply lines. The paper addresses the design of a 2-V voltage-controlled oscillator (VCO) at 2.6 GHz fabricated in a Si-bipolar process with fT of 20 GHz. The circuit bias and the transistor layout have been specifically optimized to minimize the phase noise degradation due to the intrinsic low indirect stability. A single sideband-to-carrier ratio (SSCR) of -104 dBc/Hz at 100 kHz is demonstrated with less than 14 mW power consumption.