Substitute for Flip-Flop

Discussion in 'VHDL' started by Manaryu, Oct 28, 2010.

  1. Manaryu

    Manaryu

    Joined:
    Sep 6, 2010
    Messages:
    3
    Hey,

    I have two input signals at the beginning of my design. Simple std_logic inputs with pretty similar frequencies. Up until now I've just been using a flip flop, the output with a frequency of f1-f2.

    This works without problems until the frequencies get within 0.5% of each other. (I guess due to jitter)

    After that I implemented something along the lines of:

    if rising_edge (f1) then
    Qrise <= f1;
    end if;

    invf1 <= not f1;

    if rising_edge (invf1) then
    Qfall <= not f1;
    end if;

    Q <= Qfall or Qrise;

    This increased the working range down to about 0.35% of f1.

    The problem is that I need to have something which works better than that. I guess something in the line of phase locked loops (?), but honestly I have no idea how to work with that.

    I'd really appreciate any small help here. (and if the hardware is important here I can look up the exact tools I'm using and post them later)
    Manaryu, Oct 28, 2010
    #1
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. John

    Flip Flop Synchronization

    John, Jan 3, 2004, in forum: VHDL
    Replies:
    3
    Views:
    9,633
    valentin tihomirov
    Jan 5, 2004
  2. eric
    Replies:
    15
    Views:
    1,429
  3. Weng Tianxiang

    IC area of flip-flop and SRAM?

    Weng Tianxiang, May 19, 2004, in forum: VHDL
    Replies:
    1
    Views:
    1,169
    Samuel Fuhrer
    May 23, 2004
  4. Weng Tianxiang

    Best book on a flip flop circuit

    Weng Tianxiang, May 19, 2004, in forum: VHDL
    Replies:
    1
    Views:
    802
    Mike Treseler
    May 20, 2004
  5. Jim

    Tristate Flip Flop

    Jim, Oct 27, 2004, in forum: VHDL
    Replies:
    12
    Views:
    4,849
    Ho. Li
    Nov 18, 2004
Loading...

Share This Page