The Amplifier Circuit Design Of Shortwave Therapy Apparatus

As the physical therapy has been used more and more widely in the field of modern medicine, people pay more attention to the study about the electrotherapy, phototherapy and magneto therapy equipment. Shortwave therapy is a kind of high frequency electric therapy, it plays a prominent role in the effect which can eliminate inflammation and promote the cell metabolism of the body. At present, most of the shortwave therapy apparatus in the market are based on the principle of multistage amplifier. And they usually have disadvantages of inefficiently and big loss. Therefore, designing a shortwave therapy with high performance and low loss has the important and significance research value.This project is designed from the ground up to be a shortwave therapy apparatus. The system uses class E high efficient power amplification circuit as the power generation circuit, and the simulation test of the design is proceeded by the simulation software of Pspice. The realization of RF signal generating circuit, whose output frequency is 27.12 MHz and output power is about 50 W. Design a electronic circuit by using voltage and current transformer coupler to test the Voltage Standing Wave Ratio(VSWR). And the result of the design is satisfactory, achieving the projected objectives. In the automatic impedance matching circuit, the system realizes matching impedance by using the relay to control the series and parallel capacitor in Г type matching network. And simulate the matching region of the Г type matching network by Matlab. The central processing unit part is the control circuit which can carry out immediate voltage signal processing. According to the processing result, the system controls the relay to switch status and make it do the adjustment in real-time. Add a transmission line transformer between the RF signal source and the matching network to realize the electrical isolation. In addition, put forward a kind of impedance matching algorithm which can strike a balance between matching speed and accuracy and achieve better matching results. Finally, debug and test the shortwave therapy apparatus. And the results show that the equipment achieve our intended goal.