用于超短波理疗仪的人体阻抗高频信号检波电路设计

Design of High Frequency Signal Detecting Circuit of Human Body Impedance Used for Ultrashort Wave Diathermy Apparatus

本电路是用于超短波理疗设备的人体阻抗自动调谐装置。为了判断能量发射电路与加载人体组织后的接收电路之间谐振参数是否达到最佳匹配状态,本文设计了针对高频信号的包络检波电路,配合接收电路中可变电容自动调节装置,完成阻抗匹配与调谐功能。研究通过采样线圈接收到的调幅波信号,将检波处理后的电压信号与能量发射电路中电流信号进行比对。实验显示,本电路检波处理后的电压信号波形稳定,可被低速模拟数字转换芯片(ADC)识别,且与能量发射电路电流信号正相关。检波处理后的电压值可真实表现电路谐振状态,实现人体阻抗信号采集功能。

The present circuit was designed to apply to human tissue impedance tuning and matching device in ultrashort wave treatment equipment.In order to judge if the optimum status of circuit parameter between energy emitter circuit and accepter circuit is in well syntony,we designed a high frequency envelope detect circuit to coordinate with automatic adjust device of accepter circuit,which would achieve the function of human tissue impedance matching and tuning.Using the sampling coil to receive the signal of amplitude-modulated wave,we compared the voltage signal of envelope detect circuit with electric current of energy emitter circuit.The result of experimental study was that the signal,which was transformed by the envelope detect circuit,was stable and could be recognized by low speed Analog to Digital Converter（ADC）and was proportional to the electric current signal of energy emitter circuit.It could be concluded that the voltage,transformed by envelope detect circuit can mirror the real circuit state of syntony and realize the function of human tissue impedance collecting.