An Oversampling SAR ADC With DAC Mismatch Error Shaping Achieving 105 dB SFDR and 101 dB SNDR Over 1 kHz BW in 55 nm CMOS | IEEE Journals & Magazine | IEEE Xplore

An Oversampling SAR ADC With DAC Mismatch Error Shaping Achieving 105 dB SFDR and 101 dB SNDR Over 1 kHz BW in 55 nm CMOS


Abstract:

The successive-approximation-register (SAR) architecture is well known for its high power efficiency in medium-resolution analog-to-digital converters (ADCs). However, wh...Show More

Abstract:

The successive-approximation-register (SAR) architecture is well known for its high power efficiency in medium-resolution analog-to-digital converters (ADCs). However, when considered for high-precision applications, SAR ADCs suffer from non-linearity resulting from capacitor mismatch and limited dynamic range due to comparator noise. This work presents a mismatch error shaping (MES) technique for oversampling SAR ADCs to achieve 105 dB in-band SFDR without calibration. The capacitor mismatch error is first-order high-pass filtered by simply delaying the reset of LSB capacitor array after sampling. The comparator thermal and flicker noise are also first-order shaped to high frequencies by noise shaping. The prototype in 55 nm CMOS occupies 0.072 mm2 and achieves a peak SNDR of 101 dB over 1 kHz bandwidth. It consumes 15.7 μW from a 1.2 V supply at 1 MS/s and can be configured to Nyquist mode up to 5 MS/s. These features enable the application of SAR ADCs in high-precision, multi-purpose sensor readout interfaces.
Published in: IEEE Journal of Solid-State Circuits ( Volume: 51, Issue: 12, December 2016)
Page(s): 2928 - 2940
Date of Publication: 13 September 2016

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