生成一个多周期直接信号数字合成器的Verilog代码，已在matlab中测试生成信号的频谱纯度符号要求-Generate more than one cycle of the signal direct digital synthesizer Verilog code, has been tested symbol require spectral purity of the signal generated in matlab

DDS的核心是相位累加器，相位累加器有一个累加器和相位寄存器组成，它的作用是再基准时钟源的作用下进行线性累加，当产生溢出时便完成一个周期，即DDS的一个频率周期。加载Matlab 产生的波形，通过FPGA输出DDS信号-Core DDS is the phase accumulator, a phase accumulator and phase accumulator registers, its role is to carry out a linear accumulation under