Search

An ultra-wideband voltage-controlled oscillator (VCO) in a standard 0.18-μm CMOS process is presented in this article. The designed VCO adopts two active inductors to replace the passive spiral inductors; this results in an increase in tuning-range and chip area reduction. The active inductor provides a variable inductance range from 1.7 to 3.6 nH, so that the output frequencies of the novel VCO can be obtained from 2 to 6 GHz, with a tuning-range of around 100%. According to the experimental result, it indicates that the proposed design exhibits a significant wide tuning-range and compact chip size compared with a standard VCO with passive inductors. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2311–2315, 2008; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.23655

A novel low phase-noise differential Colpitts VCO by using transformer feedback technology is presented in this paper. This work demonstrates a simple differential topology with dual-transformer approach to reduce phase-noise at low DC power consumption. A symmetrical circuit layout can be realized easily by transformers and a commonly cross-coupled structure is not adopted herein because cross couple feedback path is also a serious parasitic effect more at 10 GHz operation. Therefore, dual-transformers provide a compact feedback path and DC feed path simultaneously. Consuming a DC power of 8 mW in the VCO core, the circuit exhibits a phase-noise of −115 dBc/Hz at offset frequency of 1-MHz and the figure of merit value is −184.1 dBc.

A low phase-noise Ka-band CMOS voltage-controlled oscillator is proposed in this paper. The CMOS VCO core adopts a new complementary Colpitts structure in a 0.18- mum CMOS technology to achieve the differential-ended outputs with low phase-noise performance, as well as operate at much higher frequency. The VCO oscillates from 29.8 to 30 GHz with 200 MHz tuning range. The measured phase-noise at 1-MHz offset is -109 dBc/Hz at 30 GHz and 105.5 dBc/Hz at 29.8 GHz. The power consumption of the VCO core is only 27 mW. To the authorspsila knowledge, the proposed CMOS VCO achieves the best figure of merit (FOM) of -185 dB at 29.95- GHz band.