Is this prescaler suitable for my purpose

Discussion in 'General Electronics Chat' started by dumindu89, Sep 19, 2012.

  1. dumindu89

    Thread Starter Member

    Oct 28, 2010
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    I am going to use the SAB6456 prescaler and this have to divide the 90MHz to 110 MHz frequencies by 64.

    Input voltage to the prescaler is 200 mV(p-p).

    1. Is it possible to use this prescaler IC with this input voltage?
    2. What should be the minimum input p-p voltage that can be applied for this prescaler?
    3. How I find these minimum and maximum input voltages that can apply for the pin 2 and 3 in the datasheet?
    4. What is mean by sensitivity to input voltage in the datasheet?
    5. Do I really need to do a impedance matching?
    Datasheet >> http://cs.utsource.net/goods_files/pdf/26/26127_TEMIC_U893BSE.pdf

    6. Are there any prescaler which has divided by 8 option that satisfy my input voltage and frequency range?
     
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    The values are on page 2 of the datasheet, are you trying to input 90Mhz and hope to get out 110Mhz???

    cos that wont work, it divides the input frequency by 64 /128 /256
     
    Last edited: Sep 19, 2012
  3. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    I think the OP means a prescaler that divides by 64 an input signal that can range from 90MHz to 110MHz....output would range from 1.40625MHZ to 1.71875MHz

    Ken
     
  4. dumindu89

    Thread Starter Member

    Oct 28, 2010
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    Yeah.. you right.

    I want to know that can this prescaler detect 200 mV (p-p) input signal and output the divided frequency?

    and

    4. What is mean by sensitivity to input voltage in the datasheet?
    5. Do I really need to do a impedance matching?
     
  5. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Look at the input sensitivity graph on page 5. That will tell you the minimum RMS voltage needed to trigger the circuit. Note the variation of sensitivity in relation to input frequency.

    Matching the output impedance of your signal source will allow maximum power transfer, but not necessarily maximum input voltage.

    Ken
     
  6. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    Input sensitivity is 10mV to 20mV dependant on frequency input, page 5.
     
  7. dumindu89

    Thread Starter Member

    Oct 28, 2010
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    According the sensitivity graph 10 mV to 300 mV is the guaranteed sensitive input voltage range for my desired frequency range which means this prescaler can be used for my purpose. Isn't it?
     
  8. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Depending on good RF PCB layout practices, yes.

    Ken
     
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