AnsweredAssumed Answered

About Mixer level relationship with SA internal distortion.

Question asked by wangyiliu99 on Jul 18, 2013
Latest reply on Jul 20, 2013 by dhamilton
Hi, everyone,

I would like to ask about the setting of the SA, about Max Mixer Lvl, 
For the SA internal distortion, it is closely related to the mixer level.

My questions are
(1) How should the Max Mixer Lvl be set? Should it be set to a large value?
For my model PSA E4440A,  max. is -10dBm. 
Can I understand it like this, if the main signal into the SA is 20dBm, SA
input attenuator should be at least greater than 30dB, to make sure that the signal
level at mixer is no more than -10dBm?

(2) How the Max. Mixer Lvl setting would affect the measurement results?
Would a lower Max Mixer Lvl results in bigger default SA input attenuator value?

(3) For each SA model, there is the signal-to-distortion curve. With the x axis be "power at mixer"
y axis be "distortion dBc."
Is the following understanding correct?
Main signal f0 input to SA at power level of 10dBm, SA input attenuator is 40dB.
Power at mixer is -30dBm. 
Refer to the signal-to-distortion second order curve and find out the Y value at X= -30dBm is -60dBc. 
Can I come to the conclusion that the system internal 2nd order is 10dBm-60dB=-50dBm? Any DUT with
its 2nd order distortion performance better than 50dBm can NOT be measured via this setup. Unless, say,
SA input attenuator is increased

Your help and comments would be greatly appreciated!