Technique for Flicker Noise Up-Conversion Suppression in Differential LC Oscillators

A novel technique for the suppression of the flicker noise up-conversion in a differential LC oscillator topology is proposed. Relaxation mechanism and tunable noise filtering of the relaxation thresholds provide simultaneous suppression of differential pair and bias transistor flicker noise contributions. The proposed technique is validated on a fully monolithic oscillator architecture and 0.35-mum standard CMOS process by Cadence SpectreRF for the frequency range of 2.9-5.9 GHz. The phase noise improvement at 10 kHz offset versus a single-differential-pair LC oscillator is 6-15 dB across the tuning range.