Design Of The Power Amplifier Circuit And Control System Of The Shortwave Therapeutic Apparatus

As the continuous improvement of medical level,medical equipment is also developing rapidly.People pay more attention to medical equipment based on physical therapy such as electric therapy and magnetic therapy.Shortwave therapy apparatus is a kind of medical equipment based on electric therapy.In addition,the high-power shortwave therapy apparatus has an inhibitory effect on cancer cells.In the domestic market,most of the shortwave therapy apparatus devices use the electronic tube as the transmitting source.The electronic tube has the disadvantages of large radiation,low efficiency and short service life.Foreign Shortwave therapy apparatus is expensive and inconvenient to maintain.Therefore,it is of great significance to design a domestic shortwave therapy apparatus.This design mainly discusses the design process of shortwave therapy apparatus.The amplification part of the system uses 27.12 MHz active crystal oscillator as RF output.Then,input signal is amplified by a power amplifier.The VSWR module detects the matching state of the output to achieve the best power transmission.In this paper,ADS is used to design and analyze the power amplifier circuit.These simulations include DC simulation,stability simulation,source load traction simulation and input-output matching network simulation.According to the simulation of power amplifier circuit,when the input power is 33 dBm,the output power is 59.69dBm(931W),the output efficiency is 73.56%,and the power gain of the system is more than 26 dB.The simulation results meet the design requirements.Then,we used Altium Designer to design the schematic diagram of the amplifier system and make the circuit board.The amplification gain of the system is up to 24.96 dB through the test of the actual circuit.Finally,the output VSWR signal is detected by the coupling principle of the coupler.The system supplies the VSWR signal collected by the detection circuit to the CPU circuit for processing.According to the processing results,the CPU controls the rotation of the tuning motor,adjusts the matching of the load impedance,and realizes the automatic matching of the impedance.The system uses the CPU output to control the valve control switch and adjust the output treatment mode of the therapeutic instrument,so as to realize the regulation of multiple treatment modes.