Abstract: This paper presents an FPGA-based design scheme of NMR digital orthogonal transmitter. Utilizing embedded blocks such as RAM and the resources of logic gate of the FPGA and based on ARM7 and other communication systems, the realized transmitter is shown to be able to provide accurate high speed pulsed output with FM, PM or AM. Synchronously controlling two pieces of DDS using the FPGA, the transmitter is able to provide orthogonal RF output. In addition, both of the signals in orthogonal output can be regulated independently. This flexible design can be conveniently extended to the design of multi-channel transmitter.

Key words: NMR, transmitter, DDS, FPGA