A high-linearity low-voltage all-MOSFET delta-sigma modulator

Abstract

The implementation of a second-order switched-capacitor delta-sigma modulator is described. The modulator uses MOSFETs in their accumulation region as capacitors, with the input branches linearized using series compensation. It utilizes only basic digital CMOS technology and was fabricated in a 1.2 /spl mu/m process. The chip area of the modulator is about 1 mm/sup 2/. Measured results show that the modulator has a 94 dB peak S/THD, a 96 dB peak S/N and an 86 dB peak S/THD+N for a 6 kHz bandwidth with 5.4 mW power dissipation using a 3 V power supply and a 3.6 V capacitor bias voltage.