Designing Flip-Flops in Verilog and SystemVerilog

Flip-flops are fundamental building blocks in digital circuits that can store a single bit of information. They are used to store state information and synchronize the transfer of data between different parts of a digital system. In this post, we'll explore some common flip-flop designs in Verilog and SystemVerilog, including JK Flip Flops, D Flip-Flops, SR Flip-Flops, and T Flip-Flops.

Designing JK Flip Flops in Verilog and SystemVerilog

JK Flip Flops are used for toggling between two states. Here's an example of a JK Flip Flop in Verilog and SystemVerilog:

module JKFF (
  input  logic J, K, clk, rst,
  output logic Q, Qn
);
  always_ff @(posedge clk, posedge rst) begin
    if (rst) begin
      Q  <= 0;
      Qn <= 1;
    end else if (J && K) begin
      Q  <= ~Q;
      Qn <= Q;
    end else if (J) begin
      Q  <= 1;
      Qn <= 0;
    end else if (K) begin
      Q  <= 0;
      Qn <= 1;
    end
  end
endmodule

In this example, we've defined a module called JKFF with data input lines J, K, clk, and rst, and data output lines Q and Qn. The always_ff block triggers on the positive edge of the clock signal and the positive edge of the reset signal. The if statements inside the always_ff block determine the value of Q and Qn.

Designing D Flip Flops in Verilog and SystemVerilog

D Flip Flops are used for storing a single bit of data. Here's an example of a D Flip Flop in Verilog and SystemVerilog:

module DFF (
  input  logic D, clk, rst,
  output logic Q, Qn
);
  always_ff @(posedge clk, posedge rst) begin
    if (rst) begin
      Q  <= 0;
      Qn <= 1;
    end else begin
      Q  <= D;
      Qn <= ~D;
    end
  end
endmodule

In this example, we've defined a module called DFF with data input lines D, clk, and rst, and data output lines Q and Qn. The always_ff block triggers on the positive edge of the clock signal and the positive edge of the reset signal. The if statement inside the always_ff block determines the value of Q and Qn.

Designing SR Flip Flops in Verilog and SystemVerilog

SR Flip Flops are used for storing a single bit of data that can be set or reset. Here's an example of an SR Flip Flop in Verilog and SystemVerilog:

module SRFF (
  input  logic S, R, clk, rst,
  output logic Q, Qn
);
  always_ff @(posedge clk, posedge rst) begin
    if (rst) begin
      Q  <= 0;
      Qn <= 1;
    end else if (S) begin
      Q  <= 1;
      Qn <= 0;
    end else if (R) begin
      Q  <= 0;
      Qn <= 1;
    end
  end
endmodule

In this example, we've defined a module called SRFF with data input lines S, R, clk, and rst, and data output lines Q and Qn. The always_ff block triggers on the positive edge of the clock signal and the positive edge of the reset signal. The if statements inside the always_ff block determine the value of Q and Qn.

Designing T Flip Flops in Verilog and SystemVerilog

T Flip Flops are used for toggling between two states, much like JK Flip Flops. Here's an example of a T Flip Flop in Verilog and SystemVerilog:

module TFF (
  input  logic T, clk, rst,
  output logic Q, Qn
);
  always_ff @(posedge clk, posedge rst) begin
    if (rst) begin
      Q  <= 0;
      Qn <= 1;
    end else if (T) begin
      Q  <= ~Q;
      Qn <= Q;
    end
  end
endmodule

In this example, we've defined a module called TFF with data input lines T, clk, and rst, and data output lines Q and Qn. The always_ff block triggers on the positive edge of the clock signal and the positive edge of the reset signal. The if statement inside the always_ff block determines the value of Q and Qn.

By following these examples, you can gain a solid understanding of how to design flip flops in Verilog and SystemVerilog.