A 91dB SOP-Based Low-Voltage Low-Distortion Fourth-Order 2-2 Cascaded Delta-Sigma Modulator

[[abstract]]In this paper, a low-voltage switched-opamp-based 2-2 cascaded switehed-capacitor delta-sigma modulator in a 0.18-μm 1P6M CMOS technology is presented. The fourth-order modulator is realized using a low-distortion feed-forward topology to promote its linearity and dynamic range. The presented modulator can be operated in a wide range of supply voltage from 1.8V to 0.9V. The switched-opamp with double output stage is utilized to combine with the double-sampling technique so that the effective clocking rate can be reduced, thus also relaxing the requirement of opamp. The modulator achieves a 91 dB of SNDR within 24 kHz signal bandwidth under a 2 MHz of clocking rate. The total power consumption of this modulator is 0.86 mW under a 1V supply voltage and the chip core area is 1.57mm2.