Low phase noise 14-bit digitally controlled CMOS quadrature ring oscillator

Ramesh K. Pokharel, Prapto Nugroho, Awinash Anand, Abhishek Tomar, Haruichi Kanaya, Keiji Yoshida

Research output: Contribution to journalArticlepeer-review


High phase noise is a common problem in ring oscillators. Continuous conduction of the transistor in an analog tuning method degrades the phase noise of ring oscillators. In this paper, a digital control tuning which completely switches the transistors on and off, and a 1/f noise reduction technique are employed to reduce the phase noise. A 14-bit control signal is employed to obtain a small frequency step and a wide tuning range. Furthermore, multiphase ring oscillator with a sub-feedback loop topology is used to obtain a stable quadrature outputs with even number of stages and to increase the output frequency. The measured DCO has a frequency tuning range from 554MHz to 2.405 GHz. The power dissipation is 112mW from 1.8V power supply. The phase noise at 4MHz offset and 2.4 GHz center frequency is -134.82 dBc/Hz. The FoM is -169.9 dBc/Hz which is a 6.3 dB improvement over the previous oscillator design.

Original languageEnglish
Pages (from-to)262-269
Number of pages8
JournalIEICE Transactions on Electronics
Issue number2
Publication statusPublished - Feb 2013

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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