University of Oulu

T. H. Cheung et al., "A 3.5-GHz Digitally-Controlled Open-Loop Fractional-N Frequency Divider in 28-nm CMOS," 2020 IEEE International Symposium on Circuits and Systems (ISCAS), Sevilla, 2020, pp. 1-5, doi: 10.1109/ISCAS45731.2020.9180542

A 3.5-GHz digitally-controlled open-loop fractional-N frequency divider in 28-nm CMOS

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Author: Cheung, Tze Hin1; Martelius, Mikko1; Antonov, Yury1;
Organizations: 1Dept. of Electronics and Nanoengineering, Aalto University, Finland
2Centre of Wireless Communications – Radio Technologies, Oulu University, Finland
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 2 MB)
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Language: English
Published: Institute of Electrical and Electronics Engineers, 2020
Publish Date: 2021-01-13


This paper describes the design and measurement of an open-loop fractional frequency divider implementation. The fractional divider consists of a multi-modulus integer frequency divider (MMD), a sigma-delta modulator (SDM) and a pipelined phase interpolator. The fractional frequency division is achieved with the MMD and the 13-bit SDM toggling the integer division ratio. The resulting signal is then processed by the phase interpolator which significantly reduces the spurs by 22 dB and generates spectrally clean signal with correct output frequency. The prototype is implemented in 28-nm CMOS technology and it operates within input frequency range of 1.9 GHz–3.5 GHz with fractional division ratio in between 2–3. As an example of the operation, with a setting of an arbitrary division ratio of 2.3164 and input frequency of 2.4 GHz, the output sets correctly to 1.0361 GHz with RMS jitter of 2.1 ps.

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Series: IEEE International Symposium on Circuits and Systems proceedings
ISSN: 0271-4302
ISSN-E: 2158-1525
ISSN-L: 0271-4302
ISBN: 978-1-7281-3320-1
ISBN Print: 978-1-7281-3321-8
Pages: 1 - 5
DOI: 10.1109/ISCAS45731.2020.9180542
Host publication: 2020 IEEE International Symposium on Circuits and Systems (ISCAS), 10-21 Oct 2020, Sevilla, Spain
Conference: IEEE International Symposium on Circuits and Systems
Type of Publication: A4 Article in conference proceedings
Field of Science: 213 Electronic, automation and communications engineering, electronics
Funding: This research has been financially supported by Academy of Finland (grant 2430226211).
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