Analog-to-Digital (ADC) Verilog-A model
This article contains Verilog-A model for an Analog-to-Digital Converter (ADC).
Usage:
- Create a new cell in Library Manager named ADC and select cell type Verilog A;
- Copy and paste the code provided;
- Modify bits variable to define ADC resolution;
- Specify vmin and vmax variables to define the input signal swing;
- Specify vdd and vss variables to define output voltage levels;
- Specify tt and td variables to define rising/falling edge times and output signal delay;
- Specify dir variable to be +1 for rising and -1 for falling clock edge triggering;
- Perform Check and Save;
- A cell symbol will be created;
- Instantiate ADC cell into your design;
- Perform Check and Save and run the simulation.
ADC-DAC testbench
ADC-DAC simulation result
Cell name: ADC
Model type: Verilog-A
1// N-bit Analog to Digital Converter
2// LSB is <0>
3// Change binary_bits variable for your needs!
4// Author: A. Sidun
5// Source: AnalogHub.ie
6
7\`include "constants.vams"
8\`include "disciplines.vams"
9\`define bits 12\t\t\t\t\t// define number of binary bits here
10module ADC (out, in, clk);
11 parameter real vmin = 0.0;\t\t\t// minimum input voltage (V)
12 parameter real vmax = 1.0 from (vmin:inf);\t// maximum input voltage (V)
13 parameter real td = 0 from [0:inf);\t\t// delay from clock edge to output (s)
14 parameter real tt = 0 from [0:inf);\t\t// transition time of output (s)
15 parameter real vdd = 5;\t\t\t// voltage level of logic 1 (V)
16 parameter real vss = 0;\t\t\t// voltage level of logic 0 (V)
17 parameter real thresh = (vdd+vss)/2;\t// logic threshold level (V)
18 parameter integer dir = +1 from [-1:1] exclude 0;
19 \t\t\t\t\t\t// 1 for trigger on rising edge
20\t\t\t\t\t\t// -1 for falling
21 localparam integer levels = 1<<\`bits;
22 input in, clk;
23 output [\`bits-1:0] out;
24 voltage in, clk;
25 voltage [\`bits-1:0] out;
26 integer result;
27 genvar i;
28
29 analog begin
30 @(cross(V(clk)-thresh, dir) or initial_step) begin
31\t result = levels*((V(in) - vmin))/(vmax - vmin);
32\t if (result > levels-1)
33\t result = levels-1;
34\t else if (result < 0)
35\t result = 0;
36\tend
37
38\tfor (i=0; i<\`bits; i=i+1)
39\t V(out[i]) <+ transition(result & (1<<i) ? vdd : vss, td, tt);
40 end
41endmodule