Name of screening technique

Like Figure 9, page 14 of TI's INA321 Datasheet? Shown is an ECG amplifier circuit application.

Grant.

Are you looking for "guarding"? I've generally use this term for traces on boards used for this purpose. Leakage currents go to the "guard" trace rather than the circuit.

"Active guarding".

Thanks guys.

"guarding", "active guarding" and "ring guarding" was what I was looking for.

-Mark

Yes, I've also seen "driven guard". Note that the guard usually isn't driven at ground, but rather the common mode voltage.

I think it was invented for early ASDIC (sonar) receivers--iirc it was called the 'ghost repeater'. It has most of the vices and virtues of a transimpedance amp--you can get a big bandwidth improvement, at the price of potentially severe noise degradation.

Basically, you can't improve the SNR of the signal by jiggling the shield to make the frequency response flat--the resulting SNR is the same as if you used the same amplifier to buffer the output of the cable with the shield grounded.

Cheers

Phil Hobbs

When I used it the intention was to mitigate leakage and crosstalk in a switching network at the front end of an instrumentation amplifier. It worked well.