rate_of_change_limiter.sv

module rate_of_change_limiter #(
    parameter VCC = 12,
    parameter SAMPLE_RATE = 48000,
    parameter MAX_CHANGE_RATE = 950 // V/s
) (
    input clk,
    input I_RSTn,
    input audio_clk_en,
    input signed[15:0] in,
    output reg signed[15:0] out = 0
);
    localparam longint MAX_CHANGE_PER_SAMPLE = (MAX_CHANGE_RATE <<< 14) / VCC / SAMPLE_RATE;

    wire signed[16:0] difference;
    assign difference = in - out;
    always@(posedge clk, negedge I_RSTn) begin
        if(!I_RSTn)begin
            out <= 0;
        end else if(audio_clk_en) begin
            if(difference < -MAX_CHANGE_PER_SAMPLE)begin
                out <= out - MAX_CHANGE_PER_SAMPLE;
            end else if(difference > MAX_CHANGE_PER_SAMPLE) begin
                out <= out + MAX_CHANGE_PER_SAMPLE;
            end else begin
                out <= in; 
            end
        end
    end
endmodule