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建立了一种新型纯数字式加速度传感器的理论模型,通过检测吸合时间差检测加速度.该传感器不存在吸合电压的限制,避免了寄生电容的影响,其芯片面积远小于传统电容式加速度传感器;由于输出时间信号,可采用简单的纯数字接口电路检测.理论分析表明,质量块在两个检测电极之间的吸合时间差ΔT与加速度成正比关系,通过检测ΔT的变化即可检测加速度,其灵敏度、非线性与传统电容式加速度传感器相当.设计了一个悬臂梁-质量块结构的加速度传感器,芯片有效面积仅为0.03mm2,模拟结果显示,工作电压为8V,加速度为1gn时,吸合时间的变化ΔT为1.0554μs.采用TTL电路进行检测,其分辨率可以达到0.01gn,满量程±10gn工作时,非线性度为1.23%.
A new theoretical model of pure digital accelerometer was established to detect the acceleration by detecting the difference of the pull-in time.This sensor has no limitation of pull-in voltage and avoids the influence of parasitic capacitance, and its chip area is much smaller than that of the traditional capacitive accelerometer. Due to the output of the time signal, a simple pure digital interface circuit can be used to detect.The theoretical analysis shows that the pull-in time difference ΔT between the two detection electrodes is proportional to the acceleration, and the acceleration can be detected by detecting the change of ΔT Sensitivity and nonlinearity are equivalent to those of the traditional capacitive accelerometer.An acceleration sensor with a cantilever beam and mass structure is designed.The effective area of the chip is only 0.03mm2.The simulation results show that when the operating voltage is 8V and the acceleration is 1gn, The change ΔT is 1.0554μs. Using TTL circuit for detection, the resolution can reach 0.01gn, full scale ± 10gn work, the non-linearity is 1.23%.