Design of data acquisition system for silicon micromachined resonant accelerometer

The silicon micromeachined resonant accelerometer can transform the measured acceleration into frequency shift which is stable and reliable,so the accelerometer may get better performance.In order to getting high-resolution frequency,the counter-time must be longer.But in the use of navigation or attitude control,the counter-time is limited within a short time,10 ms.So the paper discussed the design of the data acquisition system for the silicon micromachined resonant accelerometer.The design target is that the system can acquire the differential frequency signals of the resonant accelerometer with the resolution of ±0.1 Hz,corresponding to ±1mg in 10 ms on condition that the resonant accelerometer has a normal frequency of 20 kHz,a scale factor of 100 Hz/g,and a measuring range of ±50g.A new frequency measurement method based on frequency multiplication by PLL(phase-locked loop) and the counter by the CPLD(complex programmable logic device) was introduced.The design method by using the signal shaping module,the frequency multiplication module,the counter module,and the microcontroller and the communication module of the system were also introduced.The test results given at last prove that the system designed can satisfy the target.