Title :
A low-phase-noise LC QVCO with bottom-series coupling and capacitor tapping
Author :
Yang Zhang ; Peng Liu ; Deukhyoun Heo
Author_Institution :
Sch. of Electr. Eng. & Comput. Sci., Washington State Univ., Pullman, WA
Abstract :
A novel LC Quadrature VCO (QVCO) employing bottom-series coupling and capacitor tapping to suppress phase noise at low voltage operation is presented. Placing the coupling transistors at the bottom of the switching pairs, the bottom-series coupling method yields zero resonator-phase-shift (RPS) which maximizes the quality factor (Q) of the resonator. The capacitor tapping technique allows a large signal swing at the resonator outputs while maintaining the current sources and the turned-on switching transistors in saturation. Therefore, the signal-to-noise ratio (SNR) and the loaded Q of the resonator are both boosted resulting in a low phase noise. The proposed QVCO achieves the figure of merit (FOM) of 189 dBc/Hz with a phase noise of -120.3 dBc/Hz at 1-MHz offset when operating at 6 GHz, and draws 5 mA from a 1-V power supply.
Keywords :
Q-factor; capacitors; phase noise; resonators; transistor circuits; voltage-controlled oscillators; LC quadrature voltage-controlled oscillators; bottom-series coupling; capacitor tapping; coupling transistors; current 5 mA; current sources; frequency 6 GHz; phase noise; quality factor; resonator-phase-shift; switching transistors; voltage 1 V; Capacitance; Capacitors; Circuits; Computer science; Degradation; Low voltage; Phase noise; Radio frequency; Signal to noise ratio; Transceivers;
Conference_Titel :
Circuits and Systems, 2008. ISCAS 2008. IEEE International Symposium on
Conference_Location :
Seattle, WA
Print_ISBN :
978-1-4244-1683-7
Electronic_ISBN :
978-1-4244-1684-4
DOI :
10.1109/ISCAS.2008.4541589