Help us implement a 64 MHz crystal oscillator and op-amp after it

[ahmer saeed]

there is a problem in our circuit please help to resolve it. We have implement a 64 MHz crystal Oscillator and then the OP-Amp circuit after it. Even the Op amp circuit is isolated but the 64 MHz frequency is still reaching to the OP amp thriugh ground.
If we are measuring frequency by placing both the probe of oscilloscope on ground we still attaining 64 MHz. Isn't it amazing!!

 

[yibinhsieh]

Re: please help

I think it is a normal phenomena in your case. I suggest you can use two ground plane in PCB to reduce this problem. But it can not be solved because the ground in CMOS chip is the same. We can just minimize it.

Yibin.

 

[bamdad]

Re: please help

BAD, extremely BAD ground routing. try isolating Vcc and Ground of the Crystal Oscillator with an RC network from the rest of the Gnd and Vcc nets. be sure not to use high R or Cs...