【摘要】 磁共振系统中的发射/接收（transmit/receive,T/R）开关用于收发通路的切换，要求在隔离大功率信号的同时具有较小的插入损耗；另外，在宽带磁共振谱仪中，一般的窄带T/R开关也不再适用．本文基于PIN(positive-intrinsic-negative)二极管设计了工作频率为10～100 MHz的宽带磁共振T/R开关．通过减小电平跳变、优化开关过冲和解决二极管被动导通等问题，获得了插入损耗小于1 dB、大功率信号隔离度大于75 dB、开关时间1μs的整体性能．用本文设计的宽带T/R开关替代一般探头中的窄带T/R开关，在0.5 T核磁共振（NMR）波谱仪上测得了氢核和氟核两个不同频率的磁共振信号，验证了宽带T/R开关的宽带性能．更多还原

【Abstract】 Transmit/receive(T/R) switch is used to switch the transmission and reception channels in nuclear magnetic resonance(NMR) spectrometer, which is required high isolation of high-power signals and low insertion loss of NMR signals.In addition, the general narrowband T/R switch is no longer applicable in broadband magnetic resonance spectrometer. This paper presents a positive-intrinsic-negative(PIN) diode-based T/R switch design with low insertion loss(less than 1 dB), high isolation of high-power signals(more than 75 dB) and short switching time(1 μs) in broadband(10～100 MHz). Substituting the broadband T/R switch for the narrowband T/R switch of the general probe, the NMR signals of hydrogen and fluorine nuclei at two different frequencies were measured on a 0.5 T NMR spectrometer, which verified the broadband performance of the T/R switch.更多还原