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PXA Noise source calibration (2nd stage calibration)

Question asked by midam on Oct 10, 2013

We found that even with internal pre-amp is on, the noise plot straight after the 2nd stage calibration is quite noisy especially above 26 GHz. 
As a results, we decided to add external pre-amp to cover 20 to 40GHz and performed the 2nd stage calibration and the resultant plot is much better - around 0dB across the band.

The question is, if we do 2nd stage noise source calibration with external pre-amp like this, what should we do with calibration ENR value? Does it need to be modified to address this pre-amp or would it be O.K. to use original ENR value for the calibration?

Is it O.K. to perform 2nd stage calibration with cable, pad or pre-amp attached between PXA port and noise source?

Thank you.