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:
And I use a RC filter at the front of the input, like this:
I use 10K resistor for R. And I measured the voltage drop on 'R',
- Vin = 2048mV, V_Rtop = 1.8mV. V_Rbot = -16mV
- Vin = 204.8mV, V_Rtop = -11mV, V_Rbot = -12mV
- 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?