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The benefits of technology scaling have fueled interest in realizing time-domain oversampling ( ΔΣ) of Analog-to-Digital Converters (ADCs). Voltage-Controlled Oscillators (VCO) are increasingly used to design ΔΣ ADCs because of their simplicity, high digitization, and low-voltage tolerance, making them a promising candidate to replace the classical Operational Transconductance Amplifier (OTA) in ΔΣ ADC design. This work aims to provide a summary of the fully VCO-based ΔΣ ADCs that are highly digital and scaling-friendly. This work presents a review of first-order and high-order VCO-based ΔΣ ADCs with several techniques and architectures to mitigate the nonidealities introduced by VCO, achieving outstanding power efficiency. The contributions and drawbacks of these techniques and architectures are also discussed.


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A Survey of Voltage-Controlled-Oscillator-Based ΔΣ ADCs

Show Author's information Yi ZhongNan Sun( )
Department of Electronic Engineering, Tsinghua University, Beijing 100084, China
Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX 78712, USA

Abstract

The benefits of technology scaling have fueled interest in realizing time-domain oversampling ( ΔΣ) of Analog-to-Digital Converters (ADCs). Voltage-Controlled Oscillators (VCO) are increasingly used to design ΔΣ ADCs because of their simplicity, high digitization, and low-voltage tolerance, making them a promising candidate to replace the classical Operational Transconductance Amplifier (OTA) in ΔΣ ADC design. This work aims to provide a summary of the fully VCO-based ΔΣ ADCs that are highly digital and scaling-friendly. This work presents a review of first-order and high-order VCO-based ΔΣ ADCs with several techniques and architectures to mitigate the nonidealities introduced by VCO, achieving outstanding power efficiency. The contributions and drawbacks of these techniques and architectures are also discussed.

Keywords: Voltage-Controlled Oscillator (VCO), Analog-to-Digital Converter (ADC), oversampling (ΔΣ) ADC, time-domain signal processing, VCO-based ΔΣ ADC

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Publication history

Received: 27 February 2021
Revised: 14 May 2021
Accepted: 16 May 2021
Published: 13 November 2021
Issue date: June 2022

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© The author(s) 2022

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Nos. 61934009 and 62090042), Beijing National Research Center for Information Science and Technology, Beijing Innovation Center for Future Chips (ICFC), and the Academician Expert Open Fund of Beijing Smart-chip Microelectronics Technology Co., Ltd.

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