An Nmos Cross-Coupled Quadrature Vco using Coupling Common-Gate Pmosfets

ABSTRACT This letter presents a fully integrated cross‐coupled quadrature voltage‐controlled oscillator (QVCO) using common‐gate transistor instead of common‐source transistor as a coupling device. The prototype wide‐tuning X‐band QVCO in 0.18‐μm CMOS process is proposed to generate four output phases and consists of two n‐core cross‐coupled VCOs and four pMOS coupling devices. The proposed QVCO oscillates from 8.52 to 10.56 GHz and the power consumption is 9.76 mW at 0.8 V supply voltage. The measured phase noise is −118.88 dBc/Hz at 1‐MHz offset frequency from the carrier frequency 9.86 GHz. The QVCO occupies a chip area of 0.623 × 1.197 mm2 and provides a figure of merit of −188.86 dBc/Hz. The figure of merit including tuning range, FOMT, of this QVCO is −195.30 dBc/Hz. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1705–1708, 2013