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AD5933 phase data issue

Question asked by mikeml on Dec 4, 2014
Latest reply on Dec 5, 2014 by musach



I'm programming the AD5933 chip. I'm doing several tests now to validate the data that I get from the code that I wrote.

For that I use the *default* values of the EVM board (start = 30kHz, increment frequency = 2, number of increment = 10, RFB=100K and

calibration resistor= 100K, excitation = 2V ). The gain factor that I get for mid point frequency calibration is pretty much the same as the one output by the EVM UI - for example, with the evaluation board I get "1.02013E-9" and with my code I get "1.02006E-009". I suppose this is acceptable? The computed impedance is also pretty close.

The real issue is with the phase - I get around 69 degrees with my code but the phase data when computed in the EVM is zero. What could be the reason for that?