A 440-μW, 109.8-dB DR, 106.5-dB SNDR Discrete-Time Zoom ADC With a 20-kHz BW

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This article describes a discrete-time zoom analog-to-digital converter (ADC) intended for audio applications. It uses a coarse 5-bit SAR ADC in tandem with a fine third-order delta-sigma modulator (ΔΣM) to efficiently obtain a high dynamic range. To minimize its over-sampling ratio (OSR) and, thus, its digital power consumption, the modulator employs a 2-bit quantizer and a loop filter notch. In addition, an extra feed-forward path minimizes the leakage of the SAR ADC's quantization noise into the audio band. The prototype ADC occupies 0.27 mm2 in a 0.16-μm technology. It achieves 109.8-dB DR, 106.5-dB SNDR, and 107.5-dB SNR in a 20-kHz bandwidth while dissipating 440 μW. It also achieves state-of-the-art energy efficiency, as demonstrated by a Schreier FoM of 186.4 dB and an SNDR FoM of 183.6 dB.

Original languageEnglish
Article number9312968
Pages (from-to)1207-1215
Number of pages9
JournalIEEE Journal of Solid-State Circuits
Issue number4
Publication statusPublished - 2021


  • A/D conversion
  • asynchronous SAR analog-to-digital converter (ADC)
  • audio ADC
  • delta-sigma ADC
  • discrete-time (DT) delta-sigma
  • dynamic zoom ADC
  • inverter-based operational transconductance amplifier (OTA)
  • low-power circuits
  • multi-bit quantizer


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