A class‐C quadrature VCO using the varactor coupling technique

Abstract

ABSTRACTThis letter presents a 2.1 GHz Class‐C quadrature voltage‐controlled oscillator (QVCO) working on coupling two identical Class‐C VCOs. The class‐C oscillator is used to achieve the performance of low phase noise. The QVCO uses a varactor ring to generate quadrature phase and it was implemented using the TSMC 0.18 μm CMOS 1P6M process. The output phase noise of the QVCO is −130.34 dBc/Hz at 1 MHz offset frequency from the output carrier frequency of 1.978 GHz; the quadrature phase error is 0.33° and the figure of merit is −190.61 dBc/Hz. Total power consumption is 3.9 mW. Tuning range is about 422 MHz (19%) between 1.978 and 2.4 GHz, while the control voltage was tuned from 0 V to 2 V. The die area is 0.528 × 1.168 mm2. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1961–1964, 2016