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AD8475 using IN 0.8x for aditional low pass filter?

Question asked by Alexxx on Feb 5, 2014
Latest reply on Feb 10, 2014 by ScottH

Hi,

 

I thought of using AD8475 as driver for 20 Bits 10KSPS...100KSPS SAR-ADC.

The signal frequency will be about 300Hz rectangle (chopped) and +/-10V peak.

I want to measure the DC-level with maximum possible accuracy.

1.)

Is this funnel-amp best suited for this application? Are there more precise / lower noise driver-ICs?

Current consumption / price / complexity doesn't matter.

2.)

I would like to implement an aditional low pass filter at the input. I will use the 0.4x inputs. So I thought to use

the 0.8x inputs for an additional low pass filter. Is this possible without significant degradation of low frequency parameters?

How to connect the capacitor(s)?

Would it even be possible to implement a two pole filter with that?

To get maximum DC-accuracy (and stability) I don't want an extra filter stage in front of funnel.

 

Probably this is interesting to other customers also.

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