Double-sampling highpass delta-sigma modulator with inherent frequency translation

Abstract

A double-sampling highpass delta-sigma modulator (HPDSM) with inherent frequency translation is presented. The switched-capacitor highpass filter with double-sampling not only minimizes the number of capacitors required in the feedback network but also enables chopper stabilization which makes the modulator immune to 1/f noise and DC offset. A first-order prototype HPDSM with 3 bit quantization is fabricated in 0.35 um CMOS process, and the measurement shows 56.2 dB SNR. The total power consumption is 0.65 mW, and the active die area is 0.5 mm². The proposed HPDSM can be useful in low-frequency applications such as hall-effect sensors or body area sensor network.