LVDS接口总结--(5)IDELAY3仿真

仿真参考资料如下：

 https://zhuanlan.zhihu.com/p/386057087

`timescale 1 ns/1 ps
module tb_idelay3_ctrl();parameter	REF_CLK		=  2.5        ;  // 400MHzparameter	DIN_CLK	    =  3.3        ;  // 300MHzreg			                ref_clk     ;reg			                clk_din     ;reg			                rst     ;wire                        din     ;reg   [8 : 0]               cntvaluein;wire  [8 : 0]               cntalueout  ;wire                        rdy         ;wire                        dout        ;reg   [15 : 0]              test_pattern = 16'h0c55;reg   [3 : 0]               data_cnt = 4'h0;initial beginrst = 1;ref_clk = 0;clk_din = 0;#500;rst = 0;endalways #(REF_CLK/2)  ref_clk = ~ref_clk;
always #(DIN_CLK/2)  clk_din = ~clk_din;always @(posedge clk_din or posedge rst)beginif(rst)data_cnt <= 4'd0;elsedata_cnt <= data_cnt +1'd1;endassign	din = test_pattern[data_cnt];always @(posedge clk_din or posedge rst)beginif(rst)cntvaluein <= 9'd0;else if(data_cnt == 4'd15)cntvaluein <= cntvaluein +1'd1;else;endidelay3_ctrl  u_idelay_ctrl (.ref_clk    ( ref_clk       ),.rst        ( rst           ),.din        ( din           ),.cntvaluein ( cntvaluein    ),.cntalueout ( cntalueout    ),.rdy        ( rdy           ),.dout       ( dout          ));   endmodule

module idelay3_ctrl(input									ref_clk		    ,input									rst		    ,input				            	    din		    ,input       [8 : 0]                     cntvaluein  ,output      [8 : 0]                     cntalueout  ,output                                  rdy         ,output  	                            dout	     );IDELAYCTRL #(.SIM_DEVICE("ULTRASCALE")  // Set the device version for simulation functionality (ULTRASCALE)) inst_IDELAYCTRL (.RDY(rdy), 					// 1-bit output: Ready output.REFCLK(ref_clk), 	// 1-bit input: Reference clock input.RST(rst) 		// 1-bit input: Active high reset input);	IDELAYE3 #(.CASCADE("NONE"),               // Cascade setting (MASTER, NONE, SLAVE_END, SLAVE_MIDDLE).DELAY_FORMAT("TIME"),          // Units of the DELAY_VALUE (COUNT, TIME).DELAY_SRC("IDATAIN"),          // Delay input (DATAIN, IDATAIN).DELAY_TYPE("VAR_LOAD"),           // Set the type of tap delay line (FIXED, VARIABLE, VAR_LOAD).DELAY_VALUE(0),                // Input delay value setting.IS_CLK_INVERTED(1'b0),         // Optional inversion for CLK.IS_RST_INVERTED(1'b0),         // Optional inversion for RST.REFCLK_FREQUENCY(400.0),       // IDELAYCTRL clock input frequency in MHz (200.0-800.0).SIM_DEVICE("ULTRASCALE_PLUS"), // Set the device version for simulation functionality (ULTRASCALE,// ULTRASCALE_PLUS, ULTRASCALE_PLUS_ES1, ULTRASCALE_PLUS_ES2).UPDATE_MODE("ASYNC")           // Determines whe     n updates to the delay will take effect (ASYNC, MANUAL,SYNC))IDELAYE3_inst (.CASC_OUT(),       // 1-bit output: Cascade delay output to ODELAY input cascade.CNTVALUEOUT(cntalueout), // 9-bit output: Counter value output.DATAOUT(dout),         // 1-bit output: Delayed data output.CASC_IN(1'd0),         // 1-bit input: Cascade delay input from slave ODELAY CASCADE_OUT.CASC_RETURN(1'd0), // 1-bit input: Cascade delay returning from slave ODELAY DATAOUT.CE(1'b0),                    // 1-bit input: Active-High enable increment/decrement input.CLK(ref_clk),                 // 1-bit input: Clock input.CNTVALUEIN(cntvaluein[8:0]),   // 9-bit input: Counter value input.DATAIN(),           // 1-bit input: Data input from the logic.EN_VTC(!rdy),           // 1-bit input: Keep delay constant over VT.IDATAIN(din),         // 1-bit input: Data input from the IOBUF.INC(1'b0),                // 1-bit input: Increment / Decrement tap delay input.LOAD(1'b1),               // 1-bit input: Load DELAY_VALUE input.RST(1'b0)                  // 1-bit input: Asynchronous Reset to the DELAY_VALUE);endmodule

delay tap =0	127ps
delay tap =1	131ps
delay tap =2	135ps
delay tap =3	139ps
…
delay tap =100	527ps
delay tap =200	927ps
delay tap =219	1003ps
delay tap =468	1999ps
delay tap =511	2171ps

根据上表可知  delay_tap = 127 + 4N  （N的取值为0到511）

根据简单的计算可知，双沿300M数据(对应单沿600M数据)，数据持续时间为1.66ns,取到中间需要0.83ns，对应177taps