A 28/56 GHz dual‐band CMOS VCO using reversely tunable LC source degeneration and the push–push technique

A 28/56 GHz dual‐band voltage‐controlled oscillator (VCO) using reversely tunable LC source‐degeneration and the push–push technique is demonstrated in a standard 0.13 μm CMOS process. The reversely tunable LC source degeneration is made by adding two reversely tunable LC tanks, which use varactors as the needed capacitors, to the source terminals of the cross‐coupled transistor pair of the VCO. Compared with the traditional cross‐coupled transistor pair, the proposed one significantly decreases the equivalent parallel capacitance (CEQ). This in turn results in the increase of both the operation frequency and the tuning range of the VCO. The VCO core draws 10.48 mA current from a 0.9 V power supply, that is, it only consumes 9.43 mW. The VCO achieves a tuning range of 27.7–28.7 GHz at the fundamental port and a tuning range of 55.176–58.124 GHz at the push–push port. In addition, at the fundamental port, the VCO achieves a low phase noise of −120.46 dBc/Hz at 1‐MHz offset from 28.19 GHz. The corresponding figure‐of‐merit is −199.7 dBc/Hz, one of the best results ever reported for a K‐band or Ka‐band CMOS VCO. The circuit occupies a chip area of 0.724 × 0.681 mm 2 , that is, 0.493 mm 2 , including the test pads. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2272–2278, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27046