A Class-D CMOS DCO with an on-chip LDO

Luca Fanori, Thomas Mattsson, Pietro Andreani

Research output: Chapter in Book/Report/Conference proceedingPaper in conference proceedingpeer-review


This paper presents the co-design of a class-D digitally-controlled oscillator (DCO) and a low-dropout voltage regulator (LDO) generating the supply voltage for the DCO. Despite the high intrinsic supply pushing of the class-D oscillator topology, the LDO noise has only a very marginal impact on the DCO phase noise. The class-D DCO and LDO have been integrated in a 65nm CMOS process without any thick top metal layer. The oscillation frequency is tunable between 3.0 GHz and 4.3 GHz, for a tuning range of 36%, with a fine frequency step below 3 kHz and a fine frequency range of 10MHz (both measured at 3 GHz). Drawing 9.0mA from 0.4V (corresponding to an unregulated supply voltage of 0.6 V), the phase noise is -145.5 dBc/Hz at a 10MHz offset from a 3.0 GHz carrier. The resulting FoM is 189.5 dBc/Hz, and varies less than 1 dB across the tuning range. The FoM increases to above 190 dBc/Hz when the regulated supply voltage is 0.5V.
Original languageEnglish
Title of host publicationProceedings Of The 40th European Solid-State Circuit Conference (ESSCIRC 2014)
PublisherIEEE - Institute of Electrical and Electronics Engineers Inc.
Publication statusPublished - 2014
EventEuropean Solid State Circuits Conference (ESSCIRC), 2014 - Venezia Lido, ITALY, Venice, Italy
Duration: 2014 Sept 222014 Sept 26
Conference number: 40

Publication series

ISSN (Print)1930-8833


ConferenceEuropean Solid State Circuits Conference (ESSCIRC), 2014

Subject classification (UKÄ)

  • Electrical Engineering, Electronic Engineering, Information Engineering

Free keywords

  • VCO
  • DCO
  • class-D
  • low phase noise
  • high efficiency
  • CMOS
  • low-voltage
  • LDO
  • voltage regulator


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