A 1.8 V 89.2 dB delta-sigma adc for sensor interface with on-chip reference

Abstract

A switched-capacitor (SC) third-order single-loop single-bit delta-sigma analog-to-digital converter (ADC) for sensor interface is presented. The ADC is integrated on the same chip with a bandgap reference. To reduce the power consumption, opamp bias current switching technique is adopted. The prototype delta-sigma ADC fabricated in a 0.18µm CMOS process achieves 89.2 dB dynamic range (DR), 77.1 dB signal-to-noise ratio (SNR) and 77.0 dB signal-to-noise and distortion ratio (SNDR) over 10 kHz signal bandwidth with an over-sampling-ratio (OSR) of 128. The total power consumption is 1.42 mW at 1.8 V supply.