Abstract: This paper presented an ARM- and CPLD-based design scheme for the NMR spectrometer preamplifier control system. ARM was used as the center control CPU, and CPLD as the perform unit to control the working conditions of the high-band and broadband preamplifiers, mixer and lock preamplifier. The system developed has the following main functions: 1) to convert the input TTL gate signal levels into +5V/15V signal, which is then used to control the switching between the receiver mode and the transmitter mode of the high-band and broadband preamplifiers; 2) to give users a reference signal for tuning; 3) to relay the switch channels to lock transmitter and broadband receiver in deuterium gradient shimming experiments; and 4) to display the data sent from the console PC or ADC on LED in real-time.

Key words: NMR, ²H gradient shim, tune, preamplifier control