IVC102 pcb

Gabriel Koutilellis1

Prodigy 180 points

Other Parts Discussed in Thread: IVC102, LMP7715

Dear community,

After very close examination and study of IVC102's datasheet I have made two versions of PCB layout.

I have attached pdf files of each in zip. Blue is the bottom, red is the top side.

Version one uses lmp7715 as a drive for a guard ring at 0 Volts.

Version 2 uses no drive but the guard ring is the analog ground. Version 2 also has a keepout region for the sensitive pins.

Which do you believe is better?

I can also upload eagle files and gerber files if requested.

Thank you a priori.

ivc.zip

over 11 years ago

0 John Caldwell over 11 years ago

TI__Genius 12325 points

Gabriel,

I'm partial to your second layout because it very closely follows the layout guidelines in the IVC102 datasheet. The guard ring on this PCB is very small and its unlikely that it requires the added complexity of a guard ring driver. These are typically used to drive the shield of long cables.

One other suggestion, when you are configuring an op amp in a gain of +1, its not recommended to use a resistor in the feedback path. These resistors are not effective for bias current cancellation on FET input op amps or BJT input op amps which use input current cancellation. Furthermore, they often introduce stability issues because they introduce a pole in the feedback loop by interacting with the input capacitance of the op amp.

Good luck with your project!

0 Gabriel Koutilellis1 over 11 years ago in reply to John Caldwell

Prodigy 180 points

Thank you very much for your answer.

Your suggestion is very much appreciated as, considering that I am a chemist, I didn't know that.

Do you have any reference so that I can understand better that pole thing you said?

Thank you a priori.

Gabriel

0 John Caldwell over 11 years ago in reply to Gabriel Koutilellis1

TI__Genius 12325 points

Gabriel,

This post from my (now retired) colleague Bruce Trump takes a very intuitive look at what I was referring to: link

0 Gabriel Koutilellis1 over 11 years ago in reply to John Caldwell

Prodigy 180 points

Thank you very much.

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IVC102 pcb