Design And Research On Drive And Sense Circuitry For Micro-machined Gyroscope Based On FPGA

Micro-machined vibration gyroscope has a series of features, such as small size, light weight, low cost, high reliability, easily digital, intelligent and so on. It can be widely used in aerospace, military areas, automotive industry, medical equipment and other areas. A micro-gyroscope system needs not only the sensitive element with high performance as the core device, but also the drive circuit and detecting circuit of the gyroscope is an essential part. In this paper, I research on micro-machined gyroscope designed independently by ourselves, in order to improve the performance of micro-machined gyroscope and reduce the volume of micro-machined gyroscope, the measurement and control circuit of the micro-machined gyroscope is designed and researched, the research is focus on ASIC. The measurement and control circuit mainly includes: the design and research of analog interface circuit, the design and research of the digital closed-loop drive circuit, and the design and research of the angular-rotation-rate demodulation circuit.Discussion and analysis the overall plan for the measurement and control circuit of the micro-machined gyroscope. Compared with the analog measurement and control technology, the digital measurement and control technology was selected to design and study the driving and the detection mode of gyroscope, and designed the overall plan of the measurement and control circuit of the gyroscope. The C/V conversion of the signal is realized through the differential capacitance detection circuit. Then, the drive interface circuit has been designed with a voltage follower and an inverter. The appropriate ADC and DAC have been selected through analyzing and designing the sampling frequency and quantization bits. Finally, the digital design of the micro-machined gyroscope system has been studied and designed.Research on the design and analysis of the digital closed-loop driving circuit of the micro-machined gyroscope. In the paper, the digital closed-loop driving circuit is achieved by self-oscillation and AGC. The function of AGC(automatic gain control) of the digital closed-loop driving circuit has been optimized, the control accuracy of the function has been improved. The carrier signal of the capacitance detection is obtained by CORDIC algorithm. Then, the implementation of the band pass filter and the phase shift of the digital closed-loop driving circuit have been introduced.Research on the design and analysis of the digital detection circuit of micro-machined gyroscope. The angular-rotation-rate demodulation modular of the digital detection circuit has been designed and optimized, and the stability of the angular rate signal has been improved. The low pass filter in the digital detection circuit has been designed, and the design of the low pass filter by FIR has been discussed in detail.According to the design of the analogue interface circuit, the test board is made. And the design of the digital circuit was downloaded into the FPGA. The key signal of the gyroscope is tested and the correct data is obtained. The experiments show the digital circuit designed meets the requirements of normal working for gyroscope.The implementation of the measurement and control circuit of the micro-machined gyroscope plays an important role in the improvement of the gyro performance(e.g., stability, precision, etc.), reduction of the volume and the consumption of the gyroscope.