制作出一种新型结构的谐振式硅微加速度计,其输出频率信号可以克服微机电系统器件输出微弱信号检测的困难.采用双端固定音叉作为谐振器,在加速度作用下,质量块的惯性力通过悬臂梁施加于音叉轴向,利用音叉谐振频率的变化测量加速度.在每个音叉臂上制作了梳齿结构,用梳齿间的静电力激励音叉产生谐振,并利用其构成的电容检测其振动频率.该加速度计采用体硅工艺制作,文中给出了工艺流程.用有限元方法仿真估算,得到传感器的灵敏度约为2/g Hz.
To enhance the coherence and reliability of the double-ended tuning fork （DETF） resonator, a measurement system of resonator vibration is presented to check its dynamic characteristics. Laser Doppler techniques are utilized and the relation between DETF vibration velocity and output current of photodetector is obtained. Resonator vibration equation is also analyzed and its driving power only depends on the direct current bias voltage and the amplitude of alternative voltage. Furthermore, a special resonator driving control circuit based on measurement is designed. The amplitude and frequency of circuit is controlled by a computer so that highly stable and strong driving signal can be output. Experiments on driving and measuring double-ended tuning fork have been done, The frequency of driving signal is 8 kHz and the peak-to-peak value of driving voltage is 140 V. Experimental results indicate resonator can be drived stably by driving control circuit and dynamic characteristics of DETF may be measured in real time.
