Flexible and fully integrated 4-bit SAR ADC using metal-oxide TFTs

Abstract

This paper presents a flexible fully integrated 4-bit successive approximation register (SAR) analog-to-digital converter (ADC), which is fabricated by unipolar n-type indium-zinc-oxide thin-film transistors. A bootstrap switch and a comparator with a pre-amplifier are proposed and employed to realize the SAR ADC. The fabricated SAR ADC achieves a sampling rate of up to 20 kHz and a peak signal-to-noise and distortion ratio of 22.9 dB, corresponding to an effective-number-of-bits of 3.52 bits. The static performance of −0.58/+0.37 LSB DNL and −0.49/+0.39 LSB INL is achieved.