AnsweredAssumed Answered

Wierd Spike 2 With VMC and ELO

Question asked by neilbaliga on Sep 12, 2013
Latest reply on Sep 16, 2013 by Dr_joel
This is a secondary issue to my first Spike #1 post

Using Agilent 5224 FW Rev A.09.85.06
Frequency translated device using ELO in a VMC channel

Issue #2: Swept FREQUENCY Test

Phase at ELO tuning point is (by design) 0 degrees
When sweeping across frequency, we are seeing an offset in the phase that makes the phase plot look like there is a spike at the ELO tuning point
This is because the phase plot is offset, but the phase at the tuning point is still hard set to EXACTLY 0.0 degrees and makes it look like a spike at the tuning point

This is not 100% deterministic, but occurs in nearly 20-50% of the sweeps
The  "spike" is NOT there when we switch the DUT configuration to a locked LO (leaving ELO on and all other PNA settings the same)
The  "spike" is NOT there when we switch the DUT configuration to a locked LO (turning ELO off)

When we move the tuning point, the "spike" moves accordingly to the tuning point

We have tried all variations of tuning parameters down to the mHz tuning at each sweep, but still see this issue manifest itself.
Sorry, don't have an image to show this phenomenon.

Please advise...  

Outcomes