Low power CMOS differential LC-VCO and QVCO design

Abstract

This thesis presents a backgate coupled QVCO with current reused structure, and complementary cross-coupled differential Colpitts VCO and QVCO. The formally proposed QVCO not only dissipates significantly lower power but also improves 1/$\It{f}^{3}$ close-in phase noise, compared to the conventional QVCO. For verification of the suggested idea, the proposed QVCO designed for 2 GHz operation based on a 0.18-$\mum$ CMOS technology. Measurements show -102 and -124 dBc/Hz at 100-kHz and 1-MHz offset, respectively, while dissipating a total current of 1.74 mA from a 1.25-V supply. The latterly proposed VCO is substituted gm-boosted Colpitts oscillator for the cross-coupled N-MOS switching pair in the conventional complementary cross-coupled differential LC-VCO. By reducing of supply voltage and providing high negative conductance at the given current consumption, the proposed VCO is possible to make low power design. A 1.8-GHz VCO and P-QVCO, adopting the proposed topology, are implemented in 0.25-$\mum$ CMOS technology. From the measurement result, the fabricated VCO and QVCO shows phase noise of -116.8 and -117.7 dBc/Hz at 1-MHz offset while dissipating only 0.4 and 1.1 mA from 0.9-V supply, respectively.