A Compressed Sensing Analog-to-Information Converter With Edge-Triggered SAR ADC Core

Abstract

This paper presents the design and implementation of an analog-to-information converter (AIC) capable of Nyquist and compressed sensing modes of operation. The core of the AIC is a 10-bit edge-triggered charge-sharing SAR ADC with a figure of merit (FOM) of 55 fJ/conversion-step and Nyquist-sampling rate of 9.5 Msample/s. The integration of a pseudorandom clock generator enables compressed sensing operation via random sampling and subsequent asynchronous successive approximation conversion by the core ADC. The AIC allows complete reconstruction of a spectrum consisting of sparse single tones or sparse frequency bands using compressed sensing algorithms based on ℓ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> -minimization as well as ℓ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1,2</sub> regularization, which exploits group sparsity. Implemented in 90 nm CMOS, the prototype SAR ADC core achieves a maximum sample rate of 9.5 MS/s, an ENOB of 9.3 bits, and consumes 550 μW from a 1.2 V supply. Measurement results of the AIC demonstrate an effective bandwidth of 25 MHz, which is 5 × greater than Nyquist-sampling rate with an improved effective FOM of 12.2 fJ/conversion-step for signals with sparse frequency support.