Signal Generator Based On Sopc Design

The core of Signal Generater is frequency synthesisor, the main methods are: direct analog frequency synthesis, PLL frequency synthesizer (PLL), direct digital synthesis (DDS). The circuit of analog frequency synthesis is complex, lack of flexibility and stability. PLL technology is more mature with high frequency stability, accuracy, and low prices, but the frequency of the output signal can only adjust step by step; DDS is an open-loop system without feedback, its frequency synthesis speed and frequency stability are very high. So DDS (direct digital synthesis) technology is one of the main techniques to generate signals with relatively large bandwidth, fast phase agility, fine precision and continuous phase, DDS has extensive application in communications, radar, navigation, and other modern electronic field.Domestic DDS signal generator is basically designed with DDS chips and some additional processors. In this issue, the entire signal generator system is integrated into a SOPC with only one Xilinx FPGA chip. Tthe following major achievements are made in this issue:The principle of simultaneous circuit design, not only reduce system noise, but also improve the stability of the system. Pipe-line technology is used to optimize DDS signal generator, by adding timing constraints and adoption of static timing analysis (STA), the DDS module can work under a clock of 170 Mhz.The use of digital modulation technology not only enhance the digital modulation response rate, but also greatly reduce hardware costs. Modulation block is designed to work at a clock of 182Mhz. It Use fixed-frequency to modulate base-band binary signal, with its code rate range of 0 ~ 2 Mbps.The VHDL/Verilog mixed programming and simulation technology is used in the Embedded signal generator design. It passed synthesis, timing simulation, and is verified on Xilinx XC4VFX12 FPGA chip. This signal generator, not only can generate pulse, frequency adjustable sinusoidal signal, Digital Noise, but also can generate LFM signal, and other basic modulation signal. Such as the AM,ASK,FSK and QAM.