Binary-to Thermometer Encoder model
This page contains Verilog-A model of the binary-to-thermometer encoder. This block can be used for behavioral simulation of the pipelined ADCs, programmable gains/BW etc. This model will automatically select number of outputs based on selected number of input binary bits.
Usage:
- Create a new cell in Library Manager named bin2therm and select cell type Verilog A;
- Copy and paste the code provided;
- Specify binary_bits variable to be the desired binary bits number;
- Specify Start_Bit to be 0 if you want thermometer code to start from 0 or 1 if you want thermometer code to start from 1;
- Perform Check and Save;
- A cell symbol will be created;
- Instantiate bin2term cell into your design;
- Perform Check and Save and run the simulation.
Example: binary_bits = 2, Start_Bit = 0
| Binary input | Thermometer code |
|---|---|
| 00 | 000 |
| 01 | 001 |
| 10 | 010 |
| 11 | 100 |
Example: binary_bits = 2, Start_Bit = 1
| Binary input | Thermometer code |
|---|---|
| 00 | 0001 |
| 01 | 0010 |
| 10 | 0100 |
| 11 | 1000 |
Cell name: bin2term
Model type: Verilog-A
1// Binary to Thermometer decoder
2// Implements two options:
3// Start_Bit = 0: Decimal 0 equals thermometer 0
4// Start_Bit = 1: Decimal 0 equals thermometer 1
5// Change binary_bits variable for your needs!
6// Author: A. Sidun
7// Source: AnalogHub.ie
8
9`include "constants.vams"
10`include "disciplines.vams"
11`define binary_bits 4 // define number of binary bits here
12
13module bin2therm(in,out);
14input [`binary_bits-1:0] in;
15output [2**`binary_bits-1:0] out;
16
17voltage [`binary_bits-1:0] in;
18voltage [2**`binary_bits-1:0] out;
19
20parameter real vdd = 1; // voltage level of logic 1 (V)
21parameter real vss = 0; // voltage level of logic 0 (V)
22parameter real threshold = 0.5; // logic threshold level (V)
23parameter integer Start_Bit = 0; // defines if thermometer starts from 0 or 1
24
25real dout[2**`binary_bits-1:0]; // internal result variable
26integer code;
27genvar i;
28
29analog begin
30// convert binary input to code
31 code = 0;
32 for (i = 0; i < `binary_bits; i = i + 1) begin
33 @(cross(V(in[i]) - threshold))
34 ;
35 if (V(in[i]) > threshold)
36 code = code + (1 << i);
37 end
38//$display("Code = %d", code);
39
40case (Start_Bit)
41 0: begin // Decimal 0 equals thermometer 0
42 for(i=1;i<2**`binary_bits+1;i=i+1) begin
43 if(code!=i) begin
44 dout[i-1]=vss;
45 end
46 else begin
47 dout[i-1]=vdd;
48 end
49 end
50 end
51
52 1: begin // Decimal 0 equals thermometer 1
53 for(i=0;i<2**`binary_bits;i=i+1) begin
54 if(code!=i) begin
55 dout[i]=vss;
56 end
57 else begin
58 dout[i]=vdd;
59 end
60 end
61 end
62endcase
63
64// Plotting outputs
65for (i=0; i<2**`binary_bits; i=i+1)
66 V(out[i]) <+ transition(dout[i],0,0);
67end
68endmodule