Abstract:

In nuclear magnetic resonance (NMR) systems, the radio frequency (RF) pulse generator critically influences imaging quality. Traditional direct digital synthesis (DDS) techniques rely on large-capacity lookup tables to achieve high precision, which results in excessive consumption of on-chip block random access memory (BRAM) resources and limits flexibility. This study presents a novel RF pulse generator design based on the coordinate rotation digital computer (CORDIC) algorithm. By integrating a custom CORDIC core within a field-programmable gate array (FPGA), the proposed system achieves digital modulation of RF signal’s frequency, phase, and amplitude. Combined with a Zynq-7000 system-on-chip (SoC), this design delivers a highly integrated and low-power hardware architecture. Experimental results demonstrate that the generator can output RF pulses with a frequency resolution of 0.046 Hz and a phase resolution of 0.005 5˚, while reducing BRAM resources occupied by four channels by approximately 21.4% compared to the traditional DDS solution. This design offers a feasible solution for achieving miniaturization and high performance in the RF front-end of NMR instruments.

Key words: NMR, CORDIC, radio frequency pulse generator, BRAM