Abstract:

T/R switch is a device that switches between the radio frequency (RF) transmission path and the signal reception path, and enables rapid tuning and detuning of RF coils. PIN diodes are widely utilized in modern T/R switch and tunable coil configurations, given that they operate as variable resistors controlled by DC current at RF frequencies. Since the PIN diode can only work with a driver providing the forward or reverse bias supply, its performance is significantly influenced by the capability of the driver. This paper presents a driver design with high driving speed, and high voltage and current driving capabilities. In this design, the control signal was separated from the high power driving supplies. The driver had a switching time within 500 ns with an output voltage over 400 V and an output current over 10 A. It can be applied to drive fast and high-power T/R switches.

Key words: NMR instrumentation, T/R switch driver, optoelectronic isolation, PIN diode, high power, MOSFET