A 2-GHz Differentially-Tuned VCO with Reduced Flicker Noise Up-Conversion

Differential-voltage-controlled oscillators (D-VCO) compared to their single-ended counterparts allow cancellation of common-mode bias noise and lower tuning sensitivity without compromising the frequency range. This paper describes the implementation of a novel DVCO circuit, fabricated in 0.35-μm CMOS technology together with a single-end-tuned VCO (S-VCO) for comparison. Both circuits cover the 2.0-2.4-GHz frequency range. The measured 1 f 3 phase noise of the D-VCO is –71 dBc/Hz at 10-kHz offset, which is 10 dB lower than the companion S-VCO. The 1 f 2 noise measures -136 dBc/Hz at 3 MHz, with 45-mW power consumption.