Modeling a quantiser in VHDL (synthesisable circuit)

Discussion in 'VHDL' started by vishallko31, May 5, 2006.

  1. vishallko31

    vishallko31 Guest

    Hi

    I am trying to model a quantizer for Digital PLL. What I have to do is
    something like this:

    I get a xor_pulse (which is indicative of the phase difference between
    input and output) frequency of PLL. I need to quantise this pulse in
    steps of 50 ps.

    The standard library (65 nm) that I am using has buffers whose delay
    varies from 19 to 50 ps (best and worst process).

    Now what I am doing is: I model a delay line. I instantiate 95 buffers
    (95 is the largest word that I would get) in a chain. I feed xor_pulse
    to this and chain and the progressively delayed xor_pulses are used as
    clocks to my flip-flops. The xor_pulse is fed to the D input of these
    flip flops. I tested this by simulating the circuit and it worked
    alright.

    The trouble is: Xor_pulse goes to 95 flip flops...

    1) i want that xor_pulse should not drive more than 2 cells....i want
    to limit the loading....
    2) Xor_pulse should reach all the flip flops (D pin) at the same
    time....

    what should I do to acheive the above two requirement....

    somebody please advice....

    regards
    Vishal
     
    vishallko31, May 5, 2006
    #1
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