Total views : 355

A Low Phase Noise NMOS LC-VCO using New Degeneration Structure


  • School of Electronic and Electric Engineering, Daegu University, Gyeongsan 38453, Korea, Republic of


Background/Objectives: It is necessary to reduce the contribution of a differential pair for a low phase noise LC-VCO because previous works are mainly focused on the LC tank and tail current source. Methods/Statistical Analysis: A new NMOS LC-VCO with an LC degenerated structure is proposed for linearizing a cross coupled differential pair. The NMOS LC-VCO with the proposed structure is designed using a 0.18 μm CMOS process and simulated by Spectre RF. Findings: The proposed structure is very useful for suppressing the flicker and thermal noise contribution of a cross coupled differential pair which forms a negative transconductance. Especially, the proposed structure overcomes the limitation the previous capacitive degeneration structure when it operates at higher oscillator frequency above 5 GHz. Application/Improvements: Its phase noise performance is improved about 3 dB compared with that of the conventional NMOS LC-VCO structure with no degeneration consuming the same bias current of 2mA from a 1.8 V supply.


CMOS, Degeneration, LC-VCO, LC Tank, Negative Impedance Transform, Phase Noise.

Full Text:

 |  (PDF views: 279)


  • Pengg F, Barras D, Kucera M, Scolar N, Vouilloz A. A low power miniaturized 1.95 mm2 fully integrated transceiver with fast PLL mode for IEEE 802.15.4/Bluetooth smart and proprietary 2.4GHz applications. Proc IEEE RFIC Symp; 2014. p. 71–4.
  • Moon H, Han J, Choi S-I, Keum D, Park B-H. An area-efficient 0.13 μm CMOS multiband WCDMA/HSDPA receiver. IEEE Transaction on Microwave Theory and Techniques. 2010 May; 58 (5):1447–55.
  • Rael JJ, Abidi AA. Physical processes of phase noise in differential LC oscillators. Proc IEEE CICC; 2000. p. 569–72.
  • Hegazi E, Sjoland H, Abidi AA. A filtering technique to lower LC oscillator phase noise. IEEE Journal of Solid-State Circuits. 2001 Dec; 36(12):1921–30.
  • Moon H, Nam I. 1.3 V low close-in phase noise NMOS LC-VCO with parallel PMOS transistors. IET Electronic Letters. 2008 May; 44(11):676–78.
  • Zhan JHC, Maurice K, Duster JS, Kornegayi KT. Analysis and design of negative impedance LC oscillators using bipolar transistors. IEEE Transaction on Circuits and Systems I. 2003 Nov; 50(11):1461–64.
  • Grebene AB. Analog integrated circuit design. New York: Van Nostrand; 1972.
  • Ismail A, Abidi AA. CMOS differential LC oscillator with suppressed up-converted flicker noise. IEEE International Solid-State Circuits Digest of Technical Papers; 2003. p. 98–9.


  • There are currently no refbacks.

Creative Commons License
This work is licensed under a Creative Commons Attribution 3.0 License.