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Time domain processing techniques using ring oscillator-based filter structures

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Title: Time domain processing techniques using ring oscillator-based filter structures
Authors: Leene, L
Constandinou, TG
Item Type: Journal Article
Abstract: The ability to process time-encoded signals with high fidelity is becoming increasingly important for the time domain (TD) circuit techniques that are used at the advanced nanometer technology nodes. This paper proposes a compact oscillator-based subsystem that performs precise filtering of asynchronous pulse-width modulation encoded signals and makes extensive use of digital logic, enabling low-voltage operation. First- and second-order primitives are introduced that can be used as TD memory or to enable analogue filtering of TD signals. These structures can be modeled precisely to realize more advanced linear or nonlinear functionality using an ensemble of units. This paper presents the measured results of a prototype fabricated using a 65-nm CMOS technology to realize a fourth- order low-pass Butterworth filter. The system utilizes a 0.5-V supply voltage with asynchronous digital control for closed-loop operation to achieve a 73-nW power budget. The implemented filter achieves a maximum signal to noise and distortion ratio of 53 dB with a narrow 5-kHz bandwidth resulting in an figure- of-merit of 8.2 fJ/pole. With this circuit occupying a compact 0.004-mm2 silicon footprint, this technique promises a substantial reduction in size over conventional Gm-C filters, whilst addition- ally offering direct integration with digital systems.
Issue Date: 1-Dec-2017
Date of Acceptance: 9-Jun-2017
URI: http://hdl.handle.net/10044/1/50090
DOI: 10.1109/TCSI.2017.2715885
ISSN: 1549-8328
Publisher: Institute of Electrical and Electronics Engineers
Start Page: 3003
End Page: 3012
Journal / Book Title: IEEE Transactions on Circuits and Systems Part 1: Regular Papers
Volume: 64
Issue: 12
Copyright Statement: © 2017 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.
Sponsor/Funder: Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Funder's Grant Number: EP/M020975/1
EP/K015060/1
Keywords: Science & Technology
Technology
Engineering, Electrical & Electronic
Engineering
Filtering
VCO
time-domain
asynchronous logic
low noise
delta-sigma
low voltage
mixed signal
CMOS
AMPLIFIERS
ANALOG
ADC
Electrical & Electronic Engineering
0906 Electrical and Electronic Engineering
Publication Status: Published
Open Access location: http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7971944
Online Publication Date: 2017-07-07
Appears in Collections:Electrical and Electronic Engineering
Faculty of Engineering