Papers by Author: Jun'an Liu

Abstract: This paper presents a fourth-order sigma delta (ΣΔ)modulator applied in micro-inertial sensors. After a introduction of sigma-delta modulator and its application in micro-inertial sensors, the system-level analysis and design is given and the gain coefficients is calculated. By the use of root locus, the stability of high order ΣΔ modulator is analyzed and it is got the minimum value of quantizer gain k is 0.287. The simulation shows that the signal to noise ratio (SNR) is 121.6 dB and the effective number of bits (ENOB) is 19.91 bits. When input level is smaller than -6 dBFs, the quantizer and integrators would not be overload and work well.

Abstract: In this paper a high-performance closed-loop fourth-order sigma-delta (ΣΔ) micro-accelerometer is presented. After a introduction of sigma-delta accelerometer, system-level analysis and design of a fourth-order sigma-delta micro-accelerometer is given. The simulation result shows that an accelerometer with 107dB signal to noise ratio (SNR) and 17.5 bits effective number of bits (ENOB) is achieved. Through the root locus analysis, it is got that accelerometer is stable when quantization gain is bigger than 0.262. The accelerometer gets a good linearity and it becomes overload when input signal level is greater than -5dBFS.