PIN diode driver for NMR and MRI

Designing custom coils for magnetic resonance systems, such as nuclear magnetic resonance (NMR) spectrometers and magnetic resonance imaging (MRI) scanners, often entails using non-standard configurations of the transmit-receive (T/R) switch and Q-spoiling circuits. The built-in drivers of commercial NMR and MRI systems are, typically, only reconfigurable within a narrow application range (if at all). Thus, the built-in driver may not be able to properly control the custom T/R switches and Q-spoiling circuits when using custom built coils. We present a PIN diode driver which functions in both an MRI scanner and NMR spectrometer. The PIN diode driver is based on readily available discrete components and achieves switching times for the reverse and forward bias states (transmit on and off) of 2 μs and 0.4 μs respectively. Hence, this work enables a higher degree of customization of the RF switching circuits in an MR system and is potentially of interest for designers of custom coils for both NMR spectrometers and MRI scanners.