Title :
Frequency Tuning Range Extension in LC-VCOs Using Negative-Capacitance Circuits
Author :
Qiyang Wu ; Quach, T.K. ; Mattamana, A. ; Elabd, S. ; Orlando, P.L. ; Dooley, S.R. ; McCue, Jamin J. ; Creech, G.L. ; Khalil, Waleed
Author_Institution :
Dept. of Electr. & Comput. Eng., Ohio State Univ., Columbus, OH, USA
Abstract :
We present an experimentally validated capacitance cancellation structure to increase the tuning range (TR) of LC voltage-controlled oscillators (VCOs) with minimal phase noise or power impact. The cancellation is based on an ultrawideband differential active negative-capacitance (NC) circuit. An NC scheme suitable for bottom-biased VCOs is analyzed and combined with a CMOS VCO to cancel the fixed capacitance in the LC tank. The NC structure is further modified to be tunable, enabling additional expansion of the VCO TR. By manipulating the quality factor (Q) of the NC tuning varactor pair, a prototype VCO achieves a maximum TR of 27% in a 130-nm technology, while dissipating 13 mA from a 0.9-V supply. The TR is the highest reported at Q-band, covering from 34.5 GHz to 45.4 GHz. Compared to the reference VCO without an NC circuit, the TR is increased by 38%. The measured worst case phase noise is -95 dBc/Hz at 1-MHz offset, and the FOMT is -184.9 dBc/Hz.
Keywords :
CMOS integrated circuits; LC circuits; Q-factor; active networks; capacitance; circuit tuning; integrated circuit noise; phase noise; voltage-controlled oscillators; CMOS VCO; LC tank; LC voltage-controlled oscillator; LC-VCO; NC circuit; NC structure; NC tuning varactor; VCO TR; bottom-biased VCO; capacitance cancellation structure; current 13 mA; frequency 34.5 GHz to 45.4 GHz; frequency tuning range extension; phase noise; power impact; quality factor; size 130 nm; ultrawideband differential active negative-capacitance circuit; voltage 0.9 V; $LC$ voltage-controlled oscillators (VCOs) (LC-VCOs); millimeter-wave integrated circuits; negative-capacitance (NC) circuits; wide-tuning-range VCOs;
Journal_Title :
Circuits and Systems II: Express Briefs, IEEE Transactions on
DOI :
10.1109/TCSII.2013.2251939