I'm new to PCB design, and looking for some advice. I designed a PCB shield and I'm seeing a lot of noise in my differentiator circuit. The circuit will run perfectly for about 2 min and then all of the sudden, a bunch of noise will disrupt the reading. Noise introduction

The circuit itself works just fine as tested on a breadboard, but not when its on the PCB. Not sure if this helps, but I've attached an image of the Board schematic as well.

enter image description here

I'm worried about crosstalking and temperature issues with temperature. I'm not sure if this is a common issue and I'd love some advice. Thanks.

EDIT1: Added schematic. The bandwidth I'm looking for is below 1 kHz. The power input is the 3.3 V supply and GND pins connected to my microcontroller (TIVA TM4C123GXL). enter image description here

  • 2
    \$\begingroup\$ Need a schematic also, what bandwidth do you need for your ADC readings? I don't see any bypass caps on that LTC1922, and the parasitic values on the traces will be quite high. Plus it looks like the supplies are being daisy chained, need to see what kind of power supplies you have. \$\endgroup\$
    – Voltage Spike
    Commented Jun 12, 2019 at 18:35
  • \$\begingroup\$ I added a schematic above. The power input comes from the 3.3 V and GND pins of my microcontroller. As far as the bypass caps, they would go from outputs PD2/PD3 to GND? \$\endgroup\$ Commented Jun 12, 2019 at 18:57
  • \$\begingroup\$ Is this a differentiator? It doesn't look like one to me. \$\endgroup\$
    – DKNguyen
    Commented Jun 12, 2019 at 19:18
  • \$\begingroup\$ How repeatable is the 2 minutes' time? Two minutes after when? (Are you turning multiple boards on at the same time? Can you switch power to just this block on and off and see if it is good for 2 minutes, or if the time is based on something else going on in your system?). Are there any potential sources of electrical noise or mechanical vibration nearby? \$\endgroup\$
    – Justin
    Commented Jun 12, 2019 at 19:30
  • \$\begingroup\$ This is the most repeatable issue I've seen across two different boards, but it doesn't happen every time. It seems like once the noise is begins showing, once I power it on later, the noise will continue. If I power the board on, all components turn on. There's no mechanical noise around, but what kinds of electrical noise are you referring to? \$\endgroup\$ Commented Jun 12, 2019 at 19:48


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