A Second-Order Charge Pump Noise-Shaping SAR ADC

Abstract

In this paper, a low-power, high-precision passive charge pump noise-shaping (NS) successive approximation register (SAR) analog-to-digital converter (ADC) is proposed for ultrasonic sensor applications in the Internet of Things (IoT). A residual voltage integration technique is introduced to realize a second-order noise transfer function (NTF), thereby achieving a trade-off between the power consumption and accuracy. To address the charge loss issue during the noise-shaping integration process, a charge pump (CP) voltage-multiplying principle is employed, which compensates for the charge loss to a certain extent. The proposed NS SAR ADC is implemented using a standard 180-nm CMOS process. Simulation results demonstrate that the circuit consumes 90.4μW under a 1.2V supply voltage at a sampling rate of 10MS/s. The proposed second-order NS SAR ADC achieves a signal-to-noise and distortion ratio (SNDR) of 87.55dB, an effective number of bits (ENOB) of 14.25bits, a Schreier figure of merit (FoMs) of 178dB.

Haoning Sun

Master’s Student

My research interests include circuit design of analog to digital converter for biomedical applications and noise shaping 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.

Kangkang Sun

PhD Student

My research interests include circuit design of analog to digital converter for biomedical applications and SAR ADC.

Jingjing Liu

Associate Professor

My research interests include low-power smart micro-sensor integrated circuit design, image sensors, biomedical sensors, and energy harvesting circuits.