Design of Cyclic-Coupled Ring Oscillators with Guaranteed Maximal Phase Resolution

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Journal Title
Journal ISSN
Volume Title
Conference article in proceedings
Date
2022
Major/Subject
Mcode
Degree programme
Language
en
Pages
4
1453-1456
Series
IEEE International Symposium on Circuits and Systems, ISCAS 2022, IEEE International Symposium on Circuits and Systems proceedings
Abstract
Cyclic-coupled ring oscillators (CCRO), which consist of M ring oscillators each with N inverting stages, can be used in time-domain data converters to achieve sub-gate-delay resolution and improved phase noise performance compared to a single ring oscillator (RO). However, CCROs can oscillate in several different oscillation modes, where some modes contain overlapping phases. Such in-phase oscillations severely degrade the performance of a time-domain data converter by undermining the sub-gate-delay of the CCRO. This paper presents a design method to avoid the undesired in-phase oscillation modes, and thus achieve guaranteed maximal phase resolution regardless of the oscillation mode, by properly selecting the CCRO dimensions N and M. We show, both theoretically and with transistor-level simulations, that mode-agnostic maximum phase resolution can be ensured by selecting a prime M together with an N which is co-prime with M.
Description
Publisher Copyright: © 2022 IEEE.
Keywords
coprime, cyclic-coupled ring oscillator (CCRO), phase resolution, prime, time-to-digital converter (TDC)
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Citation
Jarvinen , O , Unnikrishnan , V , Kempi , I , Stadius , K , Kosunen , M & Ryynanen , J 2022 , Design of Cyclic-Coupled Ring Oscillators with Guaranteed Maximal Phase Resolution . in IEEE International Symposium on Circuits and Systems, ISCAS 2022 . IEEE International Symposium on Circuits and Systems proceedings , IEEE , pp. 1453-1456 , IEEE International Symposium on Circuits and Systems , Austin , Texas , United States , 27/05/2022 . https://doi.org/10.1109/ISCAS48785.2022.9937816