AnsweredAssumed Answered

AC distortion with AD7606

Question asked by diverger on Aug 13, 2016
Latest reply on Aug 13, 2016 by harryh

I want to use AD7606 measure the phase difference of two AC signal. I've noticed the analogue input current of AD7606 is dependent with the input voltage, as below:

3){SW$Y`@K~``S@DNB_4F0E.png

And I use a RC filter at the front of the input, like this:

%ALWSF1Z0W}76]PV}LP9X$S.png

 

I use 10K resistor for R. And I measured the voltage drop on 'R',

 

  1. Vin = 2048mV, V_Rtop = 1.8mV. V_Rbot = -16mV
  2. Vin = 204.8mV, V_Rtop = -11mV, V_Rbot = -12mV
  3. Vin = 0V, V_Rtop = -12mV, V_Rbot = -12mV

The data is agreed with Figure 31.

But this mean, the voltage drop on R is change with the input signal amplitude. The wave shape will be distorted in some degree.

 

Any good methods to eliminate/minimize this?

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