An ultra-low-voltage VCO-based ΔΣ modulator using self-compensated current reference for variation tolerance

This paper introduces a voltage-controlled-oscillator-based (VCO-based) first-order delta-sigma (ΔΣ) modulator that uses a novel current reference to improve the robustness of the modulator at ultra-low operating voltages. The proposed current reference harnesses the difference in transistor charact...

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Main Authors: Narasimman, Neelakantan, Kim, Tony Tae-Hyoung
Other Authors: School of Electrical and Electronic Engineering
Format: Article
Language:English
Published: 2021
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Online Access:https://hdl.handle.net/10356/154553
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1545532021-12-28T04:51:27Z An ultra-low-voltage VCO-based ΔΣ modulator using self-compensated current reference for variation tolerance Narasimman, Neelakantan Kim, Tony Tae-Hyoung School of Electrical and Electronic Engineering A*STAR Institute of Microelectronics Engineering::Electrical and electronic engineering VCO-Based ΔΣ Modulator Ultra-Low Voltage This paper introduces a voltage-controlled-oscillator-based (VCO-based) first-order delta-sigma (ΔΣ) modulator that uses a novel current reference to improve the robustness of the modulator at ultra-low operating voltages. The proposed current reference harnesses the difference in transistor characteristics between weak inversion and moderate inversion to generate residue voltage, which is a function of process and temperature variations. The current generated by the proposed reference is used to bias a fully differential VCO integrator and a feedback current digital-to-analog conversion in the delta-sigma modulator for variation tolerance. Test chips designed and fabricated in 65-nm CMOS technology operate successfully at 0.3 V and achieve SNDR of 56.1 dB across 10 kHz bandwidth while consuming only 510 nW of power. This corresponds to a state-of-the-art figure of merit of 49 fJ/conv.-step. Measurement results for the proposed current reference and the modulator also demonstrate 3 × and 20 × improvement in process and temperature variation tolerance, respectively, while operating at such low voltages. Ministry of Education (MOE) The research of the project was supported by Ministry of Education, Singapore, under Grant AcRF TIER 1- 2018-T1-002-105 (RG 174/18). 2021-12-28T04:51:27Z 2021-12-28T04:51:27Z 2021 Journal Article Narasimman, N. & Kim, T. T. (2021). An ultra-low-voltage VCO-based ΔΣ modulator using self-compensated current reference for variation tolerance. Circuits, Systems, and Signal Processing, 40, 1089-1110. https://dx.doi.org/10.1007/s00034-020-01523-6 0278-081X https://hdl.handle.net/10356/154553 10.1007/s00034-020-01523-6 2-s2.0-85089582202 40 1089 1110 en RG174/18 Circuits, Systems, and Signal Processing © Springer Science+Business Media, LLC, part of Springer Nature 2020. All rights reserved.
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering::Electrical and electronic engineering
VCO-Based ΔΣ Modulator
Ultra-Low Voltage
spellingShingle Engineering::Electrical and electronic engineering
VCO-Based ΔΣ Modulator
Ultra-Low Voltage
Narasimman, Neelakantan
Kim, Tony Tae-Hyoung
An ultra-low-voltage VCO-based ΔΣ modulator using self-compensated current reference for variation tolerance
description This paper introduces a voltage-controlled-oscillator-based (VCO-based) first-order delta-sigma (ΔΣ) modulator that uses a novel current reference to improve the robustness of the modulator at ultra-low operating voltages. The proposed current reference harnesses the difference in transistor characteristics between weak inversion and moderate inversion to generate residue voltage, which is a function of process and temperature variations. The current generated by the proposed reference is used to bias a fully differential VCO integrator and a feedback current digital-to-analog conversion in the delta-sigma modulator for variation tolerance. Test chips designed and fabricated in 65-nm CMOS technology operate successfully at 0.3 V and achieve SNDR of 56.1 dB across 10 kHz bandwidth while consuming only 510 nW of power. This corresponds to a state-of-the-art figure of merit of 49 fJ/conv.-step. Measurement results for the proposed current reference and the modulator also demonstrate 3 × and 20 × improvement in process and temperature variation tolerance, respectively, while operating at such low voltages.
author2 School of Electrical and Electronic Engineering
author_facet School of Electrical and Electronic Engineering
Narasimman, Neelakantan
Kim, Tony Tae-Hyoung
format Article
author Narasimman, Neelakantan
Kim, Tony Tae-Hyoung
author_sort Narasimman, Neelakantan
title An ultra-low-voltage VCO-based ΔΣ modulator using self-compensated current reference for variation tolerance
title_short An ultra-low-voltage VCO-based ΔΣ modulator using self-compensated current reference for variation tolerance
title_full An ultra-low-voltage VCO-based ΔΣ modulator using self-compensated current reference for variation tolerance
title_fullStr An ultra-low-voltage VCO-based ΔΣ modulator using self-compensated current reference for variation tolerance
title_full_unstemmed An ultra-low-voltage VCO-based ΔΣ modulator using self-compensated current reference for variation tolerance
title_sort ultra-low-voltage vco-based δσ modulator using self-compensated current reference for variation tolerance
publishDate 2021
url https://hdl.handle.net/10356/154553
_version_ 1720447206814646272