A 10-GHz CMOS quadrature LC-VCO for multirate optical applications

• Published in: IEEE journal of solid-state circuits Vol. 38; no. 10; pp. 1626 - 1634
• Main Authors: Shenggao Li, Kipnis, I., Ismail, M.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2003; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Arrays; bimodal oscillation; Capacitors; Circuits; Clocks; CMOS; design; High speed optical techniques; Jitter; multirate; Optical feedback; Optical filters; Optical receivers; Optical transmitters; Oscillations; oscillators; phase ambiguity; Phase noise; quadrature; Quadratures; SONET; Transceivers; Tuning; voltage-controlled oscillator (VCO); Voltage-controlled oscillators
• ISSN: 0018-9200; 1558-173X; 1558-173X
• DOI: 10.1109/JSSC.2003.817258

A 10-GHz quadrature LC-VCO (QVCO) fabricated in a 0.13-/spl mu/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/sub 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.