Abstract

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Title:: Research on design method of active radio frequency switch for magnetic resonance

Author(s):: HUANG Qingming1; 2; 3; 4; LI Xiang1; ZHENG Gang2; 4; 1. School of Medical Imaging, Shanghai University of Medicine & Health Sciences, Shanghai 201318, China 2. School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China 3. Shanghai Key Laboratory of Molecular Imaging, Shanghai 201318, China 4. Institute of Medical Imaging Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China

Abstract:: Abstract: Objective In order to avoid coupling between the transmitting and receiving working modes of the radio frequency coil of the magnetic resonance imaging (MRI) system, when collecting short relaxation time signals, the switching time of the radio frequency switch should be as short as possible. Methods Based on the analysis of the passive MRI radio frequency switch circuit structure, an active MRI radio frequency switch circuit is designed with a PIN diode. The DC drive circuit controls the on and off of the PIN diode to realize the switching of the radio frequency switch, so as to achieve the active control over radio frequency switch and its situation to shorten the switching time of the RF switch. Results Advanced Design System (ADS) is used to simulate and analyze the isolation, insertion loss and voltage standing wave ratio (VSWR) of RF switching circuit, which meets the design requirements. The oscilloscope is used to analyze the port waveform of the external load of the DC drive circuit and the RF switch circuit, and the switching speed of the RF switch achieves the expected target. Conclusion The RF switch based on PIN diode can realize the active control of RF switching time, and perform well in isolation, insertion loss and noise figure.