A Second-Order Purely VCO-Based CT ΔΣ ADC Using a Modified DPLL Structure in 40-nm CMOS

Yi Zhong, Shaolan Li, Xiyuan Tang, Linxiao Shen, Wenda Zhao, Siliang Wu, Nan Sun*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)

Abstract

This article presents a power-efficient purely voltage-controlled oscillator (VCO)-based second-order continuous-time (CT) Δ Σ analog-to-digital converter (ADC), featuring a modified digital phase-locked loop (DPLL) structure. The proposed ADC combines a VCO with a switched-ring oscillator (SRO)-based time-to-digital converter (TDC), which enables second-order noise shaping without any operational transconductance amplifiers (OTAs). The nonlinearity of the front-end VCO is mitigated by putting it inside a closed loop. An array of phase/frequency detectors (PFDs) is used to relax the requirement on the VCO center frequency and thus reduces the VCO power and noise. The proposed architecture also realizes an intrinsic tri-level data-weighted averaging (DWA). A prototype chip is fabricated in a 40-nm CMOS process. The proposed ADC achieves a peak signal-to-noise-and-distortion ratio (SNDR) of 69.4 dB over 5.2-MHz bandwidth, while operating at the 260 MS/s and consuming 0.86 mW from a 1.1-V supply.

Original languageEnglish
Article number8889451
Pages (from-to)356-368
Number of pages13
JournalIEEE Journal of Solid-State Circuits
Volume55
Issue number2
DOIs
Publication statusPublished - Feb 2020

Keywords

  • Analog-to-digital converter (ADC)
  • data-weighted averaging (DWA)
  • digital phase-locked loop (DPLL)
  • digital-to-analog converter (DAC)
  • switched-ring oscillator (SRO)
  • time-domain signal processing
  • time-to-digital converter (TDC)
  • voltage-controlled oscillator (VCO)-based ΔΣ ADC
  • ΔΣ ADC

Fingerprint

Dive into the research topics of 'A Second-Order Purely VCO-Based CT ΔΣ ADC Using a Modified DPLL Structure in 40-nm CMOS'. Together they form a unique fingerprint.

Cite this