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Generating a 50MHz, 3.3v clock signal using a crystal oscillator + schmitt trigger inverter

Sailesh Vempaty
Prodigy 165 points
Other Parts Discussed in Thread: LMK00105, CDCLVC1102, LMK00304, CDCLVD2102, CDCLVP1102, BUF602

Hi,

I am looking to generate a 50MHz, 3.3Vpp [0-3.3V] clock signal using a 50MHz crystal oscillator. I was then thinking about passing this through a schmitt trigger inverter IC in order to guarantee a clean clock output. I want to know if something like this is even possible, what I should consider when doing this and a potential schmitt trigger inverter I could use. 

If this is not the best method to achieve my application then can someone suggest a better method please?

The crystal oscillator I was considering using is below:

  • 0
    TI__Mastermind 28550 points

    If you need just one clock, I expect the output of the crystal oscillator itself to be acceptable.  If you need more than one clock we offer a number of clock buffers, consider an CDCLVC1102 or LMK00105 for fan-out of LVCMOS clocks, these should met your requirements for the 3.3 V output clock. 

    CDCLVP1102/CDCLVD2102/LMK00304 will allow fan-out with differential clocks.  The LMK parts also have crystal inputs, in the case you were ever to use a crystal only, not a crystal oscillator as you've specified.

    Note that there are higher output count versions of each of these devices.  I've given the lowest output count variety in each case.

    73,
    Timothy

  • 0 in reply to Timothy T
    Prodigy 165 points

    Hi Timothy,

    Thank you for your response. I only need one clock at this stage so perhaps I will settle with the single 50MHz crystal oscillator.

    The thing is that I actually need to generate the 3.3Vpp clock signal to drive a 50 ohm load and hence I need to be able to supply at least ~65mA to the output load which is a diode laser. To do this I was thinking about passing the output of the 50MHz crystal oscillator through a high speed, high current buffer such as the  BUF602 device which would be operated at +/-5v supply rails.

    Will this type of 2 stage configuration work? I have listed the datasheets for the 50MHz crystal oscillator as well as the BUF602 buffer below.

    1) First stage: 50MHz Crystal oscillator



    2) Second Stage: BUF602 Buffer