Hello Dear Readers, Today in this post, I will provide some deep insight into the Signal Electromigration (Signal EM): Violations, Examples, and Practical Fixes. 1. Introduction: As technology nodes shrink into the deep‑submicron and nanometer regime (7nm, 5nm, 3nm and beyond), electromigration (EM) has become a first‑order reliability concern—not only for power/ground (PG) networks but also for signal nets. Signal EM failures are often underestimated because signal currents are transient and bidirectional. However, with higher switching activity, tighter metal pitches, thinner wires, and aggressive timing closure, signal EM can cause latent or early‑life failures if not addressed properly. This article explains: What Signal EM is and how it differs from PG EM Typical Signal EM violation scenarios Detailed, practical examples Root causes behind each violation Proven solutions and best practices to fix and prevent Signal EM issues 2. What is Signal Electromigration: El...
Hello Dear Readers,
Here I have giving Verilog code of 32-bit Multiplexer which is a common digital system block. A multiplexer selects an input from multiple inputs. The following code implements a 32-bit 2-to-1 multiplexer as well as a 4-to-1 multiplexer using a function. The [31:0] denotes a bus that has 32 bits. So Let's Start it code.
Verilog Code:
1) Multiplexer Using Dataflow Level:
module mux2to1 (a0,a1,s,y); // multiplexer, 32 bits
// inputs, 32 bits
input [31:0] a0, a1;
// input selection line, 1 bit
input s;
// output, 32 bits
output [31:0] y;
// ternary operator is used so if (s==1) y=a1; else y=a0;
assign y = s ? a1 : a0;
endmodule
Now there is also a function facility available in Verilog similar to C language such functions are sections of Verilog code that allow the Digital Designer to write more reusable and maintainable code. Often a function is created when the same operation is done over and over throughout Verilog code. Rather than rewriting code, one can just call the function. This prevents copy and paste errors and allows for more maintainable code: if the behavior of the function changes, it only needs to be updated in one location. One rule about functions is that they cannot have any time delay (# delay, posedge). This is one way in which they differ from tasks. For this reason, functions are used for creating combinational logic. Yes, functions are synthesizable!
Below is a list of rules for functions:
- Functions can have any number of inputs but only one output (one return value)
- The order of inputs to a function dictates how it should be wired up when called
- The return type defaults to one bit unless defined otherwise
- Functions execute immediately (zero time delay)
- Functions can call other functions but they cannot call tasks
- Functions can drive global variables external to the function
- Variables declared inside a function are local to that function
- Non-blocking assignment in function is illegal
- Functions can be automatic
The following code implements a 32-bit 4-to-1 multiplexer. A 4-to-1 multiplexer selects one input
from four inputs and needs a 2-bit selection signal. The assign statement can also be put in above the
function block or the below as shown in the below,
2) Multiplexer Using Function:
module mux4to1 (a0,a1,a2,a3,s,y); // 4-to-1 multiplexer, 32-bit
input [31:0] a0, a1, a2, a3; // inputs, 32 bits
input [1:0] s; // input, 2 bits
output [31:0] y; // output, 32 bits
function [31:0] select; // function name (= return value, 32 bits)
input [31:0] a0,a1,a2,a3; // notice the order of the input arguments
input [1:0] s; // notice the order of the input arguments
case (s) // cases:
2’b00: select = a0; // if (s==0) return value = a0
2’b01: select = a1; // if (s==1) return value = a1
2’b10: select = a2; // if (s==2) return value = a2
2’b11: select = a3; // if (s==3) return value = a3
endcase
endfunction
assign y = select(a0,a1,a2,a3,s); // call the function with parameters
endmodule
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Perfectly work the code.
ReplyDeleteExecuted code nice sir.
ReplyDeleteGood starting sir keep it up
ReplyDelete