active shield fdc2114

Hi Doug.,

At the moment we don't have any specific part number recommendation.

Regards,
Yibo

Do you know if anyone is using active shields with the FDC2114 and how they are achieving this ?

Thanks

Doug.

Hi Doug.,

The idea is that the shield and sensor should be driven with the same signal, so that there's no potential difference between them. Basically you need your op-amp to act as a voltage follower between the sensor and shield.

Regards,
Yibo

Thank you Yibo,

I realse it requires a unity gain voltage follower and this is what I am having issues with. I have tried various high gain bandwidth devices (> 300 mhz) and I am getting to much phase shift and distortion and the shielding is not good.

Thanks

Doug.

Does anyone else have any suggestions for the active shield drive circuit using the FDC2114 device ?
ThanksDoug.

Hi Yibo,
It is good to know that I am not the only one having issues with the active shield driver using FDC2114 :-) If you guys make any improvements please let me know.
I have tried the FDC1004 but the sampling time is just not fast enough for my application.
ThanksDoug.

Hi Doug.,

Sure. We'll let you know if there is any improvement.

Regards,
Yibo

Hi Yibo,

I would like to ask you,if there is any improvement in the field of active shielding?

In our proximity application we have to connect the sensing electrodes with coaxial cables (up to 2m). We were able to do it with the help of active shielding.

According to the problems we have discovered at the emc susceptibility test, we need to change the architecture of the capacitive sensing solution.

The FDC2xxx family seems to be the best choice, because of the EMI-Resistant architecture, but unfortunately we miss the active shielding capability.

We can't use passive shielding, because our application needs high sensitivity.

We would appreciate any suggestions.

Best regards,

Felix

Doug,

Have you found the solution for the active shield with the FDC2114?

Does the voltage follower improve the signal?

Thanks,

RH.

Yibo,
How would you connect the voltage follower to the IN0A and IN0B pins of the FDC2114 and to the shield?
A simple picture of the circuit would help a lot.
Thanks,
RH