An N-Type-Only a-IGZO Thin-Film-Transistor Based Nyquist-Rate 8-bit CDAC+SAR ADC Consuming 1.7mW at 32ksps and Achieving 44dB SNDR

This paper presents an 8-bit SAR-ADC design implemented using n-type-only a-IGZO devices in a TFT-on-foil technology. The ADC operates at a sampling rate of 32ksps, consuming 1.7mW, and achieves an SNDR of 44dB, resulting in a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{FOM}_{\mathrm{W}}$</tex> of 410 pJ/c.s. This performance surpasses the current state-of-the-art thin-film designs by approximately 50x, closing the gap between thin-film and Silicon design space, making all TFT flexible bioelectronic sensors feasible. The high sampling rate and accuracy allow for the digitization of signals directly on a flexible biomedical sensor, providing a digital output resistant to noise and interference.