Discussion in 'General Electronics Chat' started by Annu007, Mar 29, 2007.

  1. Annu007

    Thread Starter Member

    Jun 12, 2006
    Hi all,

    I have question regarding a buffer.

    I have 80MHz oscillator (50% duty cycle square wave) which was driving my DUT but the trace capacitance was high (100p) so the oscillator was loaded big time and therefore I was getting a really bad output.

    Then I added buffer 74HC/HCT125 (14 pin DIP package) to the output of the oscillator now I get a clean output from the oscillator but the buffer output which still sees a high trace capacitive load looks like a sine wave.

    Any suggestions
  2. Papabravo


    Feb 24, 2006
    The output stage of a 74HC/HCT device is pretty wimpy, and 80 MHz. may be a bit fast for that logic family. You might try an 74AC/ACT or even a 74F series part. This will be no magic solution however since at those frequencies your dealing with RF, transmission line theory, and impedance matching. This design may be beyond your capabilities and available tools.
  3. kender

    Senior Member

    Jan 17, 2007
    There are specialized ICs called "clock drivers". May be they can help you. On Semiconductor makes lots of them (for instance), may be you can find something useful in their app notes.
    Just $0.02