Design Of Sopc-based DDS Signal Generator

The direct digital synthesizer (DDS) signal generator using SOPC technology was described in this paper, mainly discussed in the implementation of DDS module in FPGA and control system design based on the Nios-Ⅱsoft core processor.The DDS module is the core of DDS signal generator. Here's a breakdown of the internal circuitry of a DDS device: its main components are a phase accumulator, a means of phase-to-amplitude conversion (often a waveform RAM), and a digital-to-analog converter. The phase accumulator and the waveform RAM were created in the FPGA. About these two aspects, the principle of DDS was discussed, the DDS module used in Nios-Ⅱsystem was generated with VHDL. Together with the digital-to-analog converter and amplitude control circuit, they made up the fully-formed DDS module. This DDS module can generate modulation waveform as well as the basic waveform. The migration of system is theoretically possible, for the waveform was generated by the software.The control system of DDS signal generator focused on two aspects: the configuration of Nios-Ⅱsystem and the migration ofμClinux. About the Nios-Ⅱsystem, mainly introduced how IP core are used, such as LCD controller, Nand flash controller, etc. About the software, analyzed the migration of U-boot andμClinux, and completed the related driver and the control programs.It gave much more flexibility by using FPGA as the hardware platform. It can upgrade the hardware with the advance of SOPC, without rewriting the VHDL code. The top programs and underlying driver were isolated by using theμClinux as the software platform. At last, testing and verification were done. The output waveform of oscilloscope showed that the solution was feasible.