@article{Leene:2017:10.1109/TCSI.2017.2715885,
author = {Leene, L and Constandinou, TG},
doi = {10.1109/TCSI.2017.2715885},
journal = {IEEE Transactions on Circuits and Systems Part 1: Regular Papers},
pages = {3003--3012},
title = {Time domain processing techniques using ring oscillator-based filter structures},
url = {http://dx.doi.org/10.1109/TCSI.2017.2715885},
volume = {64},
year = {2017}
}

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TY  - JOUR
AB  - 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.
AU  - Leene,L
AU  - Constandinou,TG
DO  - 10.1109/TCSI.2017.2715885
EP  - 3012
PY  - 2017///
SN  - 1549-8328
SP  - 3003
TI  - Time domain processing techniques using ring oscillator-based filter structures
T2  - IEEE Transactions on Circuits and Systems Part 1: Regular Papers
UR  - http://dx.doi.org/10.1109/TCSI.2017.2715885
UR  - http://ieeexplore.ieee.org/document/7971944
UR  - http://hdl.handle.net/10044/1/50090
VL  - 64
ER  - 

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