FPGA实现多路并行dds

基本原理

verilog代码

仿真结果
基本原理
1. 多路并行dds，传统DDS的局限性在于输出频率有限。根据奈奎斯特采样定理，单路DDS的输出频率应小于系统时钟频率的一半。但是在很多地方，要使采样率保持一致，所以，为了提高采样率，可以采样多路并行dds技术，然后并转串输出，提高采样率。

这里假设使用4个dds产生4路并行的dds，其中，4路dds的可以分别表示为：

可以从上式中看出，4路dds的pinc（频率控制字）是一样，差别是在其相位差（poff）DDS0的poff是0；DDS1的poff是fofs*1；，DDS2的poff是fofs*2；DDS3的poff是fofs*3；

假如fs是100MHz，调用4个并行的dds，然后按照顺序将4路并行的dds拼接成一路（并转串），这样就相当于采样率是4*fs,即400MHz采样率下的数据
verilog代码
1. 这里使用4路并行dds

assign dds_pinc = 32'd107374182; //fs 100m.f_out =10M 30bit ;26843545 //107374182
assign dds_poff = 32'd107374182*0; //fs 100m.f_out =10M 30bit ; 26843545
//
assign dds_pinc_1 = 32'd107374182; //fs 100m.f_out =10M 30bit ;
assign dds_poff_1 = 32'd107374182*1; //fs 100m.f_out =10M 30bit ; //26843545
//
assign dds_pinc_2 = 32'd107374182; //fs 100m.f_out =10M 30bit ;
assign dds_poff_2 = 32'd107374182*2; //fs 100m.f_out =10M 30bit ;
//
assign dds_pinc_3 = 32'd107374182; //fs 100m.f_out =10M 30bit ;
assign dds_poff_3 = 32'd107374182*3; //fs 100m.f_out =10M 30bit ;
assign dds_t_data = {dds_poff,dds_pinc};
assign dds_t_data_1 = {dds_poff_1,dds_pinc_1};
assign dds_t_data_2 = {dds_poff_2,dds_pinc_2};
assign dds_t_data_3 = {dds_poff_3,dds_pinc_3};
//
always@(posedge clk) begin 
	if(rst == 1'b1)begin 
		gen_valid <= 1'b0;
	end else if(start == 1'b1)begin 
		gen_valid  <= 1'b1;
	end else begin 
		gen_valid <= gen_valid;
	end
end

assign sin_0 = m_axis_data_tdata[31:16];
assign cos_0 = m_axis_data_tdata[15:0];
assign sin_1 = m_axis_data_tdata_1[31:16];
assign cos_1 = m_axis_data_tdata_1[15:0];
assign sin_2 = m_axis_data_tdata_2[31:16];
assign cos_2 = m_axis_data_tdata_2[15:0];
assign sin_3 = m_axis_data_tdata_3[31:16];
assign cos_3 = m_axis_data_tdata_3[15:0];
dds100m_0 dds100m_0_inst (
  .aclk(clk),                                  // input wire aclk
  .s_axis_config_tvalid(gen_valid),  // input wire s_axis_config_tvalid
  .s_axis_config_tdata(dds_t_data),    // input wire [63 : 0] s_axis_config_tdata
  .m_axis_data_tvalid(dds_data_valid),      // output wire m_axis_data_tvalid
  .m_axis_data_tdata(m_axis_data_tdata),        // output wire [31 : 0] m_axis_data_tdata
  .m_axis_phase_tvalid(),    // output wire m_axis_phase_tvalid
  .m_axis_phase_tdata()      // output wire [31 : 0] m_axis_phase_tdata
);
dds100m_0 dds100m_1_inst (
  .aclk(clk),                                  // input wire aclk
  .s_axis_config_tvalid(gen_valid),  // input wire s_axis_config_tvalid
  .s_axis_config_tdata(dds_t_data_1),    // input wire [63 : 0] s_axis_config_tdata
  .m_axis_data_tvalid(dds_data_valid),      // output wire m_axis_data_tvalid
  .m_axis_data_tdata(m_axis_data_tdata_1),        // output wire [31 : 0] m_axis_data_tdata
  .m_axis_phase_tvalid(m_axis_phase_tvalid),    // output wire m_axis_phase_tvalid
  .m_axis_phase_tdata(m_axis_phase_tdata)      // output wire [31 : 0] m_axis_phase_tdata
);
dds100m_0 dds100m_2_inst (
  .aclk(clk),                                  // input wire aclk
  .s_axis_config_tvalid(gen_valid),  // input wire s_axis_config_tvalid
  .s_axis_config_tdata(dds_t_data_2),    // input wire [63 : 0] s_axis_config_tdata
  .m_axis_data_tvalid(dds_data_valid),      // output wire m_axis_data_tvalid
  .m_axis_data_tdata(m_axis_data_tdata_2),        // output wire [31 : 0] m_axis_data_tdata
  .m_axis_phase_tvalid(m_axis_phase_tvalid),    // output wire m_axis_phase_tvalid
  .m_axis_phase_tdata(m_axis_phase_tdata)      // output wire [31 : 0] m_axis_phase_tdata
);
dds100m_0 dds100m_3_inst (
  .aclk(clk),                                  // input wire aclk
  .s_axis_config_tvalid(gen_valid),  // input wire s_axis_config_tvalid
  .s_axis_config_tdata(dds_t_data_3),    // input wire [63 : 0] s_axis_config_tdata
  .m_axis_data_tvalid(dds_data_valid),      // output wire m_axis_data_tvalid
  .m_axis_data_tdata(m_axis_data_tdata_3),        // output wire [31 : 0] m_axis_data_tdata
  .m_axis_phase_tvalid(m_axis_phase_tvalid),    // output wire m_axis_phase_tvalid
  .m_axis_phase_tdata(m_axis_phase_tdata)      // output wire [31 : 0] m_axis_phase_tdata
);