The 5.8‐GHz fully integrated low‐power low‐phase‐noise CMOS LC VCOs using RC noise‐filtering technique

Abstract

AbstractIn this work, two 5.8‐GHz fully integrated LC differential voltage‐controlled oscillators (VCOs) using standard 0.18 μm CMOS technology were implemented. One of them adopted a standard differential inductor (STD VCO). The other (PPGS VCO) comprised the same layout except that PPGS (poly‐silicon partial pattern‐ground‐shields) was added beneath its differential inductor for Q‐factor enhancement. Low‐power consumption was achieved by maximizing the equivalent parallel resistance (RP) of the LC tank by layout optimization. In addition, low‐phase noise was achieved mainly by adding two parallel capacitors to the cross‐coupled transistors and a resistor (Rfilter) to the biasing transistor for suppressing the noise coming from the current source. The STD VCO achieved a wide‐tuning‐range of 10.3% (from 5.26 GHz to 5.802 GHz) with a low‐power dissipation of 3.02 mW. The measured phase noise was −118.25 dBc/Hz at 1‐MHz offset. The corresponding figure‐of‐merit (FOM) was −188.72 dBc/Hz, better than those of the reported state‐of‐the‐art CMOS LC VCOs in 5‐GHz‐band. The chip area was only 508 × 595 μm2 excluding the test pads. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2907–29117, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23859