The Digital To Analog Mixed Circuit Design Of Micro Gyroscope Based On Band-Pass ?? Modulator

With the performance improvement of micro gyroscope, the requirement of the interface circuits is also improved. Compared with the analog interface circuits, the digitized design of the interface circuits can increase flexibility and decrease complexity. Meanwhile, the integrated design of the interface circuits can reduce the circuit area, reduce the influence of parasitic parameters and improve system accuracy. The system level simulation of the micro gyroscope digital to analog mixed circuit based on the band-pass ?? modulator was executed in this paper and the digital design of the drive loop of micro gyroscope was simulated successfully. In addition, the integrated circuit including C/V conversion circuit, phase locked loop circuit and modulator were designed and the layout of the circuits was finished by using 0.5um CMOS process.First, the review of integrated and digital design of micro gyroscope interface circuits is presented in this paper. Then, the basic principle of analog to digital converter involved in the micro gyroscope digital to analog mixed circuit based on the band-pass ?? modulator is briefly introduced. And the advantages and disadvantages between Nyquist ADC and oversampling ADC were compared. Based on the oversampling ADC, the low-pass ?? modulator and band-pass EA modulator are introduced. By comparing the advantages and disadvantages of different modulator structures, the negative feedback single tube structure of the modulator was adopted in this paper.Then, the behavioral simulation was executed by Matlab/Simulink. The simulation results show the signal to noise ratio can reach 86.4dB and the significant digit is about 13. Considering the non-ideal factors, the non-ideal modulator model was simulated and the optimal circuit parameters were determined. The digital drive loop based on band-pass ?? modulator of the micro gyroscope was simulated successfully which prove the micro gyroscope micro gyroscope digital to analog mixed circuit is feasible. The clock self-locking technology is applied in this paper which can generate sampling clock from the drive loop vibration signal for the band-pass modulator.Finally, all the circuits block including PFD, CP, LPF, VCO, frequency divider, OTA, comparator, switches, one bit DAC feedback circuit, clock circuit, bandgap reference and switch capacitance CV circuit are designed and simulated by Cadence. The overall circuit simulation results show that the signal to noise ratio is about 74.1dB, the significant digits is about 12.