As an important part of modern electronic equipment, the direct digital frequency synthesizer (DDS) has been widely used in the electronic fields due to its fast conversion time, high frequency accuracy and wide bandwidth. This design combines the flexible field-programmable gate array (FPGA) and DDS, adopts the top-down modular design idea, the pipeline structure of the feedback network and the frequency self-increasing design to achieve the frequency sweep effect. Based on the CORDIC algorithm, the phase-amplitude conversion is realized to reduce hardware resource consumption. Finally, the simulation test is carried out in the quartus II development environment. The amplitudes of sine wave and sine wave calculated by CORDIC algorithm are 32 768 and 56 758 (in 16-bit decimal system), respectively. The relative errors of the output sin and cos values compared with the expected results are only 6.1×10^-5 and 9.9×10^-5, respectively. The simulation results show that the design scheme can effectively solve the problems of large spurious components, high delay and high power consumption of DDS in the conventional surface acoustic wave wireless passive sensing system.