Impedance Matching In Medical Ultrasonic Endoscope System

With the rapid development of modern medical technology, the ultrasoundendoscope has been widely applied in modern medicine. Medical ultrasoundendoscope uses biopsy channel to bring miniature ultrasound probe into humandigestive tract. The images of gastrointestinal wall achieved by rotated scanning of thein vivo probe are used for assistant diagnoses. This imaging detection means has theadvantages of non-invasive and non-radiation, and is currently the first choice ofmedicine for the detection of human internal organs.Medical ultrasonic endoscope technology has been widespread used in medicine,but there are still some gaps on research and development of the technology betweendomestic and some foreign companies and institutions, especially in developing intoproduce and Transition. Our group has been committed to independent research anddevelopment of ultrasonic endoscope system for several years, and is currentlyworking on developing it to make practical use as equipment. In this paper, theelectrical performance of the experimental system, particularly the signals in theanalog circuit, are corresponding improved and as a result, better output signalstrength and signal-to-noise ratio are achieved.The main works of this paper are:1. Through the analysis of the signal quality in the system, it is determined toimprove overall system performance by examining the adjustment of impedancematching.2. Impedance matching analysis of ultrasound stimulated emission circuit andadjustment and improvement of the original excitation circuit are completed. MOStransistor switches and the RF (radio frequency) transformer inspire boost encoding ofthe transmitted signal. After the study of impedance matching law between transmitterand circuit, the adjustability of the transducer matching emission is realized. In orderto achieve a unified ultrasonic transmitter system with compatibility of differentmodels of probe, the paper attempted to design an adaptive transducer matchingsystem which can automatically match the intrinsic parameters depending on theultrasonic transducer. 3. The paper has studied the matching problem of the ultrasonic signalreception amplification circuit. After in combination with analog circuits of thetransmission line impedance matching problem, the adjustment of matching problemsamong the multi-stage amplifier circuit, the protection circuit and the band-pass filtercircuit are completed. The gain of received low noise amplifier circuit is improvedand as a result, the analog output signal-to-noise ratio is upgraded.4. Through the above-described regulation of improvements, the circuithardware improvement is collated and completed. The simulation circuit of thetransceiver integrated medical ultrasonic endoscope system is designed and produced.In addition, voltage regulator power supply circuit, isolation circuit, protection circuitare integrated to form a more perfect whole, for further improvement and upgrade inpractical application and test.