Low‐voltage/low‐power 7‐GH Z transformer‐coupled current‐reused CMOS QVCO with wide tuning range

In this article, we report the design of a transformer‐coupled current‐reused quadrature voltage‐controlled oscillator (QVCO) having low‐voltage operation, low‐power consumption, and a wide tuning range.An improved trifilar transformer that is fabricated by symmetrically interlacing two half circle secondary coils between the turns of the primary coil is proposed to provide a higher magnetic coupling factor. A QVCO integrated with such a trifilar transformer is implemented using 0.18‐μm RF CMOS technology. When the QVCO is operated at a supply voltage of 1V at 7.263 GHz, the measured phase noise is −111.4 dBc/Hz at a 1‐MHz offset. Further, the QVCO core draws only 1.58 mW. The total tuning range is ∼510 MHz over the whole tuning range (from 0 to 1.8 V). The calculated figure of merit is 186.6 dB and the power‐frequency‐tuning‐normalized factor is −9.4 dB. As compared to the reported data in a previous study, a 28.2% reduction in power consumption and a 54.5% increase in tuning range can be achieved. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:797–801, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25058