Pre-Emphasis with IIR Filter

Hello!

this is my new version. i tried to solve the problem with the assignments.

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL; 
entity PREemphase is
    
    
    Port (     
            Input           : in  signed (13 downto 0);
            Output         : out signed (14 downto 0);
            CLK              : in  STD_LOGIC;
            RST             : in  STD_LOGIC
         );
            
    end PREemphase;
            
architecture verhalten of PREemphase is
--signal X     : signed (13 downto 0);
signal Xi    : signed (13 downto 0);
signal Xi1   : signed (13 downto 0);
begin
    filter: process(RST, CLK)
    --variable Xi         : signed (13 downto 0); 
    variable Yn         : signed (21 downto 0); 
    --variable Xi1         : signed (20 downto 0); 
    variable Yn_tmp     : signed (21 downto 0); 
    variable Yn_tmp2     : signed (21 downto 0); 
    variable b0_var     : signed ( 7 downto 0); 
    variable div        : signed ( 7 downto 0); 
    
    begin
        if (RST = '0') then
            --Xi    := (others => '0');
            --Xi1     := (others => '0');
            Yn_tmp     := (others => '0');
            Yn_tmp2    := (others => '0');
            b0_var     := ("01100001"); --97
            div        := ("01100100"); --100
            Yn        := (others => '0');
            
            
        elsif (clk'event AND clk = '1') then
            --X <= Input;
            Xi             <= Input; --new value
            Yn_tmp     := Xi1 * b0_var;
            Yn_tmp2    := Yn_tmp / div;
            Yn            := resize(Xi, Yn'length) - Yn_tmp2;
            
            Output       <= resize(Yn, Output'length);
            Xi1            <= Xi; --old value
            
        end if;
    end process;            
    
end verhalten;

I fixed the output, so that it has one more bit. The higher frequencies are ok now, but the lower frequencies are still very attenuated. For example a signal f=100Hz nearly disappears after the filter.

The thing is that normally the frequencies below 3.18 kHz have to go through without any increase oder decrease.

@parrado: Thank you for the code. I will check it out!!