A Low-Parasitic and Common-Centroid Cross-Coupled CMOS Transistor Structure for High-Frequency VCO Design

• Published in: IEEE electron device letters Vol. 30; no. 5; pp. 532 - 534
• Main Authors: LEE, In-Young, YUN, Seok-Ju, OH, Seung-Min, LEE, Sang-Gug
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.05.2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Circuit properties; CMOS; CMOS technology; common-centroid; cross-coupled transistor layout; Design. Technologies. Operation analysis. Testing; Devices; Dissipation; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Exact sciences and technology; Fingers; gain cell layout; Integrated circuit interconnections; Integrated circuits; low parasitic; Noise; Oscillators, resonators, synthetizers; Parasitic capacitance; Phase noise; Radio frequency; Routing; Semiconductor devices; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Transistors; Tuning; voltage-controlled oscillator (VCO); Voltage-controlled oscillators; Wideband; Phase noise; Performance evaluation; Multivariable control; Voltage controlled oscillator; Spurious capacity; common-centroid; Tuning; cross-coupled transistor layout; gain cell layout; CMOS; Complementary MOS transistor; Operating rate; low parasitic; Interconnection; Complementary MOS technology; Integrated circuit; Capacitance; Parasitic resistance; High frequency; voltage-controlled oscillator (VCO); Gain
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2009.2015472

This letter reports a cross-coupled transistor structure that allows simple routing, induces no gate-drain overlap interconnect capacitances, minimizes the parasitic resistances of interconnects, allows smaller drain-junction parasitic capacitances, and provides inherent common-centroid characteristic, all of which help to improve the high-frequency and wideband performances of CMOS voltage-controlled oscillators (VCOs). The proposed cross-coupled transistor structure is applied for a 26.2-GHz differential VCO design which dissipates 7.3 mA from 1.8-V supply using 0.18-mum CMOS. Measurements show 2.1-GHz, 29%, and 4-dB improvements in operating frequency, tuning range, and phase noise compared to those of the VCO using a conventional cross-coupled transistor layout, respectively. The VCO with the proposed transistor structure shows the phase noise of -113.7 dBc/Hz at 1 MHz, which corresponds to FOM and FOMT of -190.4 and -194 dBc/Hz, respectively.