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Gain and phase measurement using AD8302

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anushaas

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Hi,

I am using an AD8302 IC for gain and phase measurement of two signal inputs within a frequency range of 1Hz to 1MHz.

It is mentioned in the Application Note AN-691 that the IC need to be used in the following configuration to enable its use in low frequency applications.

1.png

I used a +5V supply,CC= 10uF and CFLT = 1uF.Also R1=R2 =51.9 Ohm.

The signal inputs were VINA =VF1 and VINB = VF2 as shown in the following circuit:

2.png

The voltage outputs of AD8302 corresponds to Gain and Phase measurements as per the following equations given in datasheet:

3.png

where VCP =900mV,RFISLP = 600mV/decade and RFIQ = 10mV/degree as per datasheet at low frequencies.

I acquired a bode plot for the same circuit using the Bode Analyser of NI Elvis II+ and also obtained the Gain in dB and Phase in degree using the above equations from the AD8302 output voltages.

The graphs obtained were as follows:

4.png

5.png

Can anyone please suggest ways to reduce the error in the gain and phase measurements?
 

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