A 2nd Order Delta-Sigma ADC for Pressure Sensor Interface

A second order delta-sigma analog-to-digital converter (ADC) including a bandgap reference, a bias circuit for sensor, and a digital filter for the interface of piezoresistive pressure sensor is presented. The proposed sensor interface circuit is designed to target a pressure range from 0 to 100 psi. The prototype sensor interface circuit is implemented in a 0.35 μm CMOS process. The single-loop, 1-bit, second-order delta-sigma ADC operates at OSR of 256 achieves 80.5 dB dynamic range (DR), 79.6 dB peak signal-to-noise ratio (SNR), and 74.4 dB peak signal-to-noise and distortion ratio (SNDR) over a signal bandwidth of 7.8 kHz with 3.3V supply while consuming 0.33mW including on-chip reference and bias current for sensor. (in Performance Summary: 0.95mW)