In order to simplify design of analog circuit and reduce interference of anolog circuit

a Σ-Δ modulation micro-accelerometer based on digital circuit is presented. Field programmable gate array（ FPGA） is used to implement the PID circuit based on structure of traditional Σ-Δ interface circuit designed with pure analog circuit.PCB circuit is designed and a 2nd-order Σ-Δ closed-loop interface with its sample frequency 50 k Hz is built. Test results show that sensitivity of accelerometer is 1. 4 V / gn

and the closed-loop noise density is less than 400 μgn/Hz1 /2.