A 5GHz 370fsrms 6.5mW clock multiplier using a crystal-oscillator frequency quadrupler in 65nm CMOS

Karim M. Megawer, Ahmed Elkholy, Daniel Coombs, Mostafa G. Ahmed, Ahmed Elmallah, Pavan Kumar Hanumolu

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Phase noise performance of ring-oscillator-based (RO-based) clock multipliers is typically limited by oscillator noise. The most power-efficient method for improving the phase noise of such clock multipliers is by increasing the oscillator noise suppression bandwidth (FBW). While FBW depends on the type of clock multiplier, the maximum achievable FBW is limited by the reference frequency (Fref). For instance, in phase-locked loops (PLLs) FBW = Fref/10, while multiplying delay-locked loops (MDLLs) [1] and injection-locked clock multipliers (ILCMs) [2] can achieve FBW of Fref/4 and Fref/6, respectively. Exploiting this behavior, the MDLL in [1] and the ILCM in [2] achieved excellent performance at the expense of using a high-frequency low-noise reference (REF) clock and a small multiplication factor (N < 10). One promising way to reduce Fref in MDLLs/ILCMs involves increasing the injection rate by using both the positive and negative edges of the REF clock [3, 4] but at the cost of making jitter/spurious performance susceptible to duty cycle errors in the REF clock. While [3] demonstrated an effective means to correct such errors, it still needed a relatively high Fref of 125MHz. In view of this, we present a method to quadruple the frequency of a conventional 54MHz Pierce XO and demonstrate its application using an RO-based ILCM achieving less than 370fsrms integrated jitter at a 5GHz output. The proposed quadrupler acts as a low noise XO frequency multiplier and can be used to increase the bandwidth of MDLLs and ring/LC-based integer-or fractional-N PLLs also.

Original languageEnglish (US)
Title of host publication2018 IEEE International Solid-State Circuits Conference, ISSCC 2018
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages3
ISBN (Electronic)9781509049394
StatePublished - Mar 8 2018
Event65th IEEE International Solid-State Circuits Conference, ISSCC 2018 - San Francisco, United States
Duration: Feb 11 2018Feb 15 2018

Publication series

NameDigest of Technical Papers - IEEE International Solid-State Circuits Conference
ISSN (Print)0193-6530


Other65th IEEE International Solid-State Circuits Conference, ISSCC 2018
CountryUnited States
CitySan Francisco

ASJC Scopus subject areas

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

Fingerprint Dive into the research topics of 'A 5GHz 370fs<sub>rms</sub> 6.5mW clock multiplier using a crystal-oscillator frequency quadrupler in 65nm CMOS'. Together they form a unique fingerprint.

Cite this