Abstract
Aiming to meet the requirements of high resolution and low power consumption for biosensors, this paper presents a 0.47-mW 1.44-mm2 fourth-order single-bit switched-capacitor (SC) Delta-Sigma modulator (DSM) ADC in 3.3-V 0.18- μm CMOS technology. Through modeling and system design, circuit design, and layout design, the DSM circuit achieves a peak SNDR of 109.3 dB and a peak SNR of 110.2 dB for a biosensor system with a signal bandwidth of 1 kHz and an oversampling ratio (OSR) of 128. Compared with traditional circuit structures, the improved Recycling Folded-cascode (RFC) Fully Differential Operational Transconductance Amplifier effectively reduces nearly half of the power consumption at the same resolution. The obtained 172.6-dB FOMS is competitive within the high-resolution (SNDR > 100 dB) and low-power (power < 5mW) SC DSM ADCs .