Title :
Analytical and experimental study of tuning range limitation in mm-wave CMOS LC-VCOs
Author :
Qiyang Wu ; Elabd, S. ; McCue, Jamin J. ; Khalil, Waleed
Author_Institution :
Dept. of Electr. & Comput. Eng., Ohio State Univ., Columbus, OH, USA
Abstract :
In this paper, we present an analytical model for predicting the tuning range of CMOS mm-wave LC voltage-controlled oscillators (LC-VCOs). A detailed analysis of the frequency dependent quality factor (Q) of the LC-tank is performed to characterize the tank loss. The frequency dependent Q is used to size the transconductance (gm) of the cross-coupled pair to satisfy the VCO startup condition. The relationship between the cross-coupled pair gm and the operating frequency is also derived. With the above relationships, the frequency dependent tuning range is further calculated and compared with simulation results. To verify the analysis, three CMOS mm-wave VCOs are fabricated in a 130 nm CMOS process. The measured tuning range of the 26 GHz, 34 GHz and 40 GHz VCO is 25%, 21% and 18%, respectively, which is consistent with the presented tuning range model.
Keywords :
CMOS analogue integrated circuits; Q-factor; coupled circuits; losses; microwave integrated circuits; microwave oscillators; millimetre wave integrated circuits; millimetre wave oscillators; voltage-controlled oscillators; LC-tank; cross-coupled pair; frequency 26 GHz; frequency 34 GHz; frequency 40 GHz; frequency dependent quality factor; mmwave CMOS LC-VCO; size 130 nm; tuning range limitation; voltage-controlled oscillator; CMOS integrated circuits; Capacitance; Inductors; Transistors; Tuning; Varactors; Voltage-controlled oscillators;
Conference_Titel :
Circuits and Systems (ISCAS), 2013 IEEE International Symposium on
Conference_Location :
Beijing
Print_ISBN :
978-1-4673-5760-9
DOI :
10.1109/ISCAS.2013.6572379
