A Multi-Rate 9.953–12.5-GHz 0.2- /22m SiGe BiCMOS LC Oscillator Using a Resistor-Tuned Varactor and a Supply Pushing

Abstract

A multi-rate 9.953–12.5-GHz low phase noise LC oscillator was realized in a 90-GHz 0.2 m SiGe BiCMOS process. It achieves a 36% tuning range by combining a 35% open-loop frequency calibration range having a sub-0.1% residual error with a 1% closed-loop varactor frequency tuning. The oscillator gain is below 130 MHz/V , while having less than 10% variation over the entire tuning range. The varactor is realized with multiple parallel-connected cells consisting of constant capac- itors and voltage-controlled resistors that bring a lower process variation and a higher quality factor in comparison with standard diode and MOS varactors. A dual regulator architecture was used to provide both high PSRR and low output voltage noise. The supply pushing was reduced below 100 kHz/V by using a pushing cancellation circuit that balances the negative and positive voltage coefficients of the different nonlinear capacitors connected to the LC tank. A discrete-time automatic amplitude control loop using a variable tail resistor architecture was implemented to optimize the VCO’s phase noise performance. The VCO specifications include 9.953–12.5-GHz frequency range, 0.1% frequency calibration error, 122 dBc/Hz phase noise at 1 MHz offset, /51kHz /49 /51 corner frequency, 80 dBc spurious tones, 250 400 m/50die area and 5-mA bias current from a 3.3-V supply.