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Design >> Analog Design >> sense resistance change
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Message started by avlsi on Jul 8^th, 2006, 9:01am

Title: sense resistance change
Post by avlsi on Jul 8^th, 2006, 9:01am

hi,

I would like to know the various methods to sense resistance change between 1 Mega Ogm to 30 Mega Ohm. It should be able to sense a change of 1% or below.

Please tell me how to find things on this.

Thanks in advance

Title: Re: sense resistance change
Post by schmitt on Jul 20^th, 2006, 2:51am

Hi,
Probably you can pump a known current and sense the voltage drop across the resistance. There can be some feedback loop which generates an error voltage by comparing the voltage drop with a fixed reference. This error voltage in turn could be used to minimize resistance variation.

Title: Re: sense resistance change
Post by matthewliao on Jul 21^st, 2006, 3:26am

or you can use a sample resistance in series of your resistance ; to ensure the accuracy, you can measure both
the votages of the sample resistance and your resistance.

Title: Re: sense resistance change
Post by loose-electron on Aug 1^st, 2006, 7:36pm

1 Meg to 30 Meg...

Yikes!

I do not know what you are trying to do, but if that is a resistance on a PCB, it is going to be sensitive to dust and humidity. It won't pass the "damp finger test" ;D for a robust board design.

If that is a resistance inside a chip, unless it is a specialized process, it will get swamped due to leakage to bulk effects.

What are you trying to do here?

thanks,
Jerry