A Second-Order Noise-Shaping SAR ADC for Biomedical Sensor Applications
Abstract
This paper proposes a low-power, area-efficient, and high-precision fully passive second-order noise-shaping (NS) successive approximation register (SAR) analog-to-digital converter (ADC) for a portable multi-channel biosignal recorder to detect abnormal action potentials in epilepsy. The proposed fully passive noise-shaping technique achieves a second-order noise transfer function (NTF) using only switchedcapacitor and a single-input-pair comparator, resulting in significant benefits in power consumption and accuracy. The power consumption is further reduced and the circuit area is minimized by employing a split-segmented capacitor digital-toanalog converter (CDAC) array. The proposed second-order NS SAR ADC is implemented using a 180 nm CMOS process with an area of 0.3×0.28 mm2. Simulation results show that the circuit consumes 86μ W at a 1.2 V supply voltage when the sampling rate is 10MS/s. It achieves a signal-to-noise and distortion ratio (SNDR) of 92.66 dB, an effective number of bits (ENOB) of 15.1bits, a bandwidth of 80 kHz, a Schreier figure of merit (FoMs) of 182.3 dB, and a Walden figure of merit (FoMw) of 15fJ/conv.-step.
Haoning Sun
Master’s Student
My research interests include circuit design of analog to digital converter for biomedical applications and noise shaping SAR ADC.
Kangkang Sun
PhD Student
My research interests include circuit design of analog to digital converter for biomedical applications and SAR ADC.
Yuchen Wang
Master’s Student
My research interests include the design of high dynamic range and multi-mode image sensors.
Wenji Mo
Master’s Student
My research interests include circuit design of low-power RISC-V processors and self-powered SoCs.
Feng Yan
PhD Student
My research interests include circuit design of analog front end for biomedical applications and sensor interfaces.
Jingjing Liu
Associate Professor
My research interests include low-power smart micro-sensor integrated circuit design, image sensors, biomedical sensors, and energy harvesting circuits.