Can anyone suggest a test setup for measuring AD8333 quadrature demod phase accuracy?
Looking at the datasheet, it seems that the demodulation accuracy was verified using an oscilloscope. Suitable signals are applied the RF and 4LOP inputs. Remembering that the signal applied to the 4LOP input is internally divided down by a factor of four before being applied to the demodulator proper, the frequency on 4LOP should be approximately four times the frequency on the RF input (RFxP and RFxN). There should be a slight frequency offset between FREQrf and FREQlo/4. In the datasheet a 20 KHz delta is used. It is also a good idea to phase lock the two signal generators together. Usually, signal generators have 10 MHz reference inputs and/or outputs that can facilitate (i.e. set up one signal generator as the master and the other as the slave).
Once this has been set up, the output signals on IxxO and QxxO can be viewed on an oscilloscope. These signals should both be equal to the frequency delta discussed earlier (i.e. 20 KHz). To check to see if the phase between the I and Q outputs is correct, an oscilloscope will have to be used which has a phase delta math function.
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