Two-order low-power sigma-delta modulator with SC techniques

Abstract

This paper presents a sigma-delta modulator of two-order with switched-capacitors (SC) techniques for low power in 0.18um CMOS process. Without continues current transmission SC techniques present a discrete low power system. And a low power op amplifier with discrete common-mode feedback and a dynamic comparator is also designed. This new amp works under the supply of 1.8v and with the direct current of 200uA. The tool Matlab is used to simulate the behavior system, while Cadence is used to design the circuit and the layout in 0.18 um CMOS (1.8v model) process. The modulator achieves 81dB dynamic range in 24-kHz signal bandwidth with OSR=128. And it consumes 0.8mW under 1.8v supply voltage.