电容式微机械超声换能器的驱动电路设计

摘要

电容式微机械加工超声换能器(cMUT)具有频带宽、灵敏度高等优点,而设计高压高频的驱动电路则是实现其优异性能的前提.针对现有驱动电路体积过大等问题,在对换能器简化模型做有限元分析求得其工作电压基础上,提出了用FPGA控制8片脉冲发射专用芯片HV7350直接驱动换能器64阵元的方案.并对其中一个通道进行了验证,产生的30VPP、400 kHz脉冲使换能器能够在0.5 m距离下接收到4.4VPP的一次回波信号.本驱动电路具有高度集成,操作简单,幅值可调,频率可控的特点,为cMUT的应用提供了可行的参考.%Capacitive micromachined ultrasonic transducer has the advantages of wide frequency band,high sensitivity and so on.However,the design of high voltage high frequency drive circuit is the precondition for realizing the excellent performance.In order to solve the problem that existing driver circuit is too large,based on Ansys simulation on simplified model of capacitive micromachined ultrasonic transducer to got operating voltage,the scheme that using FPGA to control 8 special pulse chips HV7350 to drive cMUT'64 array directly was proposed.One channel was experiment.It was shown that 30 VPP、400 kHz pulse generated by this drive circuit can drive cMUT at distance of 0.5m successfully,and get 4.4 VPP echo.This drive circuit has advantages of highly integrated,simple operation,adjustable amplitude,controllable frequency,providing a feasible reference for the applications of capacitive micromachined ultrasonic transducer.