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

Like • Show 0 Likes0
Comment • 4

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!

Yours,
Yiliu

No one else has this question

Outcomes

wangyiliu99 Sep 24, 2013 3:15 AM

if anyone knows some application note about the max mixer level setting, would you please share that with me.

I am now studying the 5952-0292 application note "SA fundaments"

Thanks a lot

Actions

dhamilton @ wangyiliu99 on Jul 19, 2013 3:59 PM

If you look on the data sheet the mixer levels and specifications for the different frequencies are listed. It is on the website.

Actions

wangyiliu99 @ dhamilton on Sep 24, 2013 3:15 AM

thanks a lot for your reply.

One more question, are there any rule-of-thumb or guidelines for the setting of the max. mixer level?

BR,
Yiliu

Actions

dhamilton @ wangyiliu99 on Jul 20, 2013 12:46 PM

Every different analyzer had different specifications but most are around -30 to -40 dBm fundamental to mixer in heterodyne mode and sometimes higher levels in preselected mode. That is why you need to have the data sheet for each unit to know what is maximum allowed based on a known clean carrier to test with. We use 5 stage 11 pole Butterworth filters with a 80 dB per octave cutoff. You can look up Telonic Berkley or K & L filters to get the filters best for test. They are expensive but will give you to correct setup needed to test your devices 2nd harmonics.

Also, a Chebyshev Type II will work also. Both of these depend on the carrier frequency for best characteristics.

Actions

4 Replies

wangyiliu99 Sep 24, 2013 3:15 AM
Mark Correct
Correct Answer
if anyone knows some application note about the max mixer level setting, would you please share that with me.

I am now studying the 5952-0292 application note "SA fundaments"

Thanks a lot
Like • Show 0 Likes0
Actions
- dhamilton @ wangyiliu99 on Jul 19, 2013 3:59 PM
  Mark Correct
  Correct Answer
  If you look on the data sheet the mixer levels and specifications for the different frequencies are listed. It is on the website.
  Like • Show 0 Likes0
  Actions
  - wangyiliu99 @ dhamilton on Sep 24, 2013 3:15 AM
    Mark Correct
    Correct Answer
    thanks a lot for your reply.
    
    One more question, are there any rule-of-thumb or guidelines for the setting of the max. mixer level?
    
    BR,
    Yiliu
    Like • Show 0 Likes0
    Actions
    - dhamilton @ wangyiliu99 on Jul 20, 2013 12:46 PM
      Mark Correct
      Correct Answer
      Every different analyzer had different specifications but most are around -30 to -40 dBm fundamental to mixer in heterodyne mode and sometimes higher levels in preselected mode. That is why you need to have the data sheet for each unit to know what is maximum allowed based on a known clean carrier to test with. We use 5 stage 11 pole Butterworth filters with a 80 dB per octave cutoff. You can look up Telonic Berkley or K & L filters to get the filters best for test. They are expensive but will give you to correct setup needed to test your devices 2nd harmonics.
      
      Also, a Chebyshev Type II will work also. Both of these depend on the carrier frequency for best characteristics.
      Like • Show 0 Likes0
      Actions

About Mixer level relationship with SA internal distortion.

Outcomes

Related Content

Recommended Content