Dynamic Power of SRAM less than Static Power

[abhishektyagi]

Hello,
I am using PrimeTime to do some power analysis of an SRAM of size 128KB generated using Arm Artisan 7nm compiler. The testbench for the same looks like the following:

module sram_tb;

    parameter integer SRAM_MACRO_SIZE = 156;
    parameter integer NUM_SRAM_MACROS = 6553;
    parameter integer ADDR_WIDTH = 15;
    parameter integer MEM_SIZE  = 1 << ADDR_WIDTH;
    parameter integer DATA_WIDTH = 32;

    reg clk;
    reg [31:0] dataout ;//[NUM_SRAM_MACROS - 1 : 0];
    reg [14:0] address;
    reg [31:0] datain;
    reg write_enable;
    reg read_enable;
    reg chip_enable;
    reg stov;
    reg [2:0] ema;
    reg [1:0] emaw;
    reg emas;
    reg ret;
    reg qnap;
    reg rawl;
    reg [1:0] rawlm;
    reg wabl;
    reg [1:0] wablm;

    //clock generation
    always #1.5 clk = ~clk;

    sram_sp_uhde dut(
       `ifdef POWER_PINS
       .VDDCE(1'b1),
       .VDDPE(1'b1),
       .VSSE(1'b0),
       `endif
       .Q(dataout),
       .CLK(clk),
       .CEN(chip_enable),
       .GWEN(write_enable),
       .A(address),
       .D(datain),
       .STOV(1'b0),
       .EMA(3'b111),
       .EMAW(2'b11),
       .EMAS(1'b1),
       .RET(1'b0),
       .QNAP(1'b0),
       .RAWL(1'b0),
       .RAWLM(2'b0),
       .WABL(1'b1),
       .WABLM(2'b0)
       );

  // Test stimulus
  initial begin
    // Initialize signals
    clk = 0;
    address = 15'b000000000000011;
    datain = 32'b00000000000000000000000000000010;
    write_enable = 1;
    chip_enable = 0;
    read_enable = 0;

    //loadmem("random_numbers.txt");

    //for (int i = 0; i < MEM_SIZE; i = i + 1) begin
    $display("SRAM[%0d]: %b", address, dataout);
    repeat (1) @(posedge clk) //address <= 4; //datain <= 2 % (1 << DATA_WIDTH);
    $display("SRAM[%0d]: %b", address, dataout);
    repeat (1) @(posedge clk) //address <= 4; //datain <= 2 % (1 << DATA_WIDTH);
    $display("SRAM[%0d]: %b", address, dataout);
    repeat (1) @(posedge clk) //address <= 4; //datain <= 2 % (1 << DATA_WIDTH);
    $display("SRAM[%0d]: %b", address, dataout);
    //// End simulation
    $finish;
  end
endmodule

I am trying to get the power numbers for a single read operation performed on the SRAM. I have verified that the testbench above give me correct output from the SRAM. But the power numbers looks like this:

Net Switching Power  = 3.000e-05   ( 0.93%)
  Cell Internal Power  = 2.877e-03   (88.79%)
  Cell Leakage Power   = 3.331e-04   (10.28%)

I am wondering what could be the reason that static power is dominating the dynamic power in this case? Should it not be the other way around?

 

[oratie]

In your example, the dynamic power (cell internal) is 88% of total power. While static (leakage) is just 10%. So dynamic is dominating.

 

[abhishektyagi]

In your example, the dynamic power (cell internal) is 88% of total power. While static (leakage) is just 10%. So dynamic is dominating.

Thank you for your response.

My understanding is that switching power is the dynamic power. Or is that not correct?

 

[oratie]

Yes, but "Net switching power" is dynamic power dissipated by external (to sram) wireloads. While "Cell internal" is dynamic power dissipated inside sram.

 

[abhishektyagi]

Yes, but "Net switching power" is dynamic power dissipated by external (to sram) wireloads. While "Cell internal" is dynamic power dissipated inside sram.

I see. Is there a reference for looking at the definition of these terms?

 

[ThisIsNotSam]

I see. Is there a reference for looking at the definition of these terms?

the documentation of your tool will give the precise meaning. and examples.