A 10-GHz quadrature LC-VCO (QVCO) fabricated in a 0.13-m CMOS process for 10-Gb/s multirate optical applications is described. Bimodal oscillation behavior (or phase ambiguity) inherent to quadrature LC-VCOs is analyzed theoretically and a cascode-based coupling method is proposed which effectively eliminates bimodal oscillation. Digitally controlled capacitor arrays are used in this design to extend the tuning range of the QVCO to cover multirate operations. The QVCO achieves a jitter generation of only 32 mUI pp at 10 GHz and a phase noise of 95 dBc/Hz at 1-MHz frequency offset with only 8 mA of current consumption in the QVCO core.
A downconversion mixer for wideband CDMA application is designed and fabricated in a 0.5 p.m CMOS technology. The mixer operates at 2.4 GHz frequency with a 3 V power supply and consumes only 4.5 mW power. Targeting in designing high performance mixers of high yield within short design cyde, this paper addresses RF mixer design issues from an optimization and statistical point of view, and derived the noise equation based on a simple noise model of the Gilbert-cell mixer. The mixer achieved a conversion gain of 14.3 dB, a SSB noise figure of 10.4 dB, and an IIP3 of -8 dBm.
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