QUADRATURE CROSS-COUPLED VCO IMPLEMENTED WITH BODY INJECTION-LOCKED FREQUENCY DIVIDERS

This article presents a CMOS quadrature voltage-controlled oscillator (QVCO). The LC-tank QVCO consists of two cross-coupled nMOS divide-by-2 injection-locked frequency divider (ILFDs) with a tail transistor, which serves the role of frequency doubler. The output of the tail transistor in one ILFD is injected to the bodies of the nMOSFETs in the other ILFD. The proposed CMOS QVCO has been implemented with the TSMC 0.18 mu m CMOS technology and the die area is 0.595 x 0.896 mm(2). At the supply voltage of 0.6 V, the total power consumption is 2.4 mW. The free-running frequency of QVCO is tunable from 5.44 to 5.8 GHz as the tuning voltage is varied from 0.0 to 0.6 V. The measured phase noise at 1 MHz frequency offset is -115.62 dBc/Hz at the oscillation frequency of 5.44 GHz and the figure, of merit (FOM) of the proposed QVCO is -186.6 dBc/Hz. (C) 2009 Wiley Periodicals. Inc. Microwave Opt Technol Lett 51: 1918-1921, 2009 Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24495