Design of modified comb filter in Sigma-Delta micro accelerometer

In order to improve the performance of the comb filter in Sigma-Delta micro accelerometer and promote the output SNR,the comb filter is modified through adjusting its zero location. According to the research results,the modified comb filter exhibits different quantizing noise filtering capabilities corresponding to different zero locations,and then,the genetic algorithm is employed to attain the optimum zero location which leads to the minimum output quantizing noise. By comparing the amplitude-frequency characteristic of the modified comb filter with that of a fourth-order comb filter,it is proved that the modified comb filter has a rapid cut-off characteristic,which means that the modified comb filter functions much better than the existing comb filter with the criterion of quantizing noise filtering capability.