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AD8302 calibration

Question asked by ssp on Dec 15, 2015
Latest reply on Dec 16, 2015 by ssp

Hi!

Greetings!


I have designed a single tone (150MHz) reflectometer circuit using AD8302. I am struggling since more than two months in just to achieve measured reflection coefficients same as the ideal ones as mentioned in col.5 in the following table.


Please take a quick look at the data mentioned below.

 

I got following results while applying resistive terminations:

For my application, above error (data mentioned in red) is very significant and cannot be ignored. Please let me know, what is the way to overcome these errors. Suggest me the steps required to calibrate AD8302.

 

Please note that in actual case, my terminating load is the complex impedance.

 

8302 Measurement voltage (mag/angle) output range measured= ~ 200mV to 1600mV

Further, it was also ensured that 8302 operates within the input as well as output voltage range as described in the datasheet.

 

Abstract circuit flow:

15dBm VHF source->35dB attenuation-> Incident wave fed to INPA of 8302

Reflected power->20dB attenuation-> reflected wave fed to INPB of 8302

 

Please note that high directivity (45dB) minicircuit’s couplers are used

 

Please guide me in this regard as soon as possible.

 

Thank you,

Sanket

(RF design engineer)

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