Questions tagged [guard]

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Designing a guard ring for a transimpedance amplifier

I am at that stage of a PCB design where I need some guidance on guard rings. The Application: The application is a photodiode circuitry (using a pin photodiode and transimpedance amplifier.) The ...
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  • 151
6 votes
3 answers
486 views

Opamp Guard Polygon: Only in Top PCB layer or or all layers

I have an opamp circuit as shown below. My board stack up is SIGNAL-GND-POWER-SIGNAL. I am providing a polygon to Guard the trace which is going to non-inverting the input of the opamp. The guard ...
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  • 604
5 votes
1 answer
189 views

Considerations for PCB guard ring trace for PH probe

Long time lurker first time poster. I have questions regarding PCB guard rings in a pH meter circuit. I know that a typical combination pH electrode has really high output impedance so you want low ...
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  • 51
3 votes
1 answer
153 views

How to fix oscillations in cable guard drive?

I am designing a guard drive for a coaxial cable, to drive its shield as a guard for low leakage measurements. After seeing some issues in the sim, I arrived at the following minimum circuit which ...
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