Hi Groups,
I am studying the app. note "recommendations for testing high power amplifiers using the pna microwave analyzers".
For the p.22, I don't understand how comes the source provides -42~13dBm but it becomes -40~-12dBm after the 20dB source attenuation ?
Looks like the source attenuation does not affect the power level ?
Thanks.
I went back and found the app note that this diagram came from and I think the problem is looking at the diagram out of context from the explanation that proceeds it (and also a bad case of proper labeling of the diagram). This section is describing a particular Gain Compression measurement setup where the author is trying to achieve a power sweep range of -10 to +18 dBm at the input to the DUT using a 34 dB Gain external amplifier. If you work backward, you see that the PNA source would have to be set to a power sweep of -44 to -16 dBm. However as you can see in the table right above this diagram the minimum source power with 0 dB attenuation is -27 dBm. So to achieve the desired power range, in this example, the author is setting the source step attenuator to 20 dB. So the power range label that you highlighted at the top of the diagram is the power setting in the UI for port 1, because in the PNA firmware the user sets the power level relative to the port and not relative to the source (i.e. the 20 dB attenuation is already included in the power setting). Now since there is additional path losses internally, to achieve -44 to -16, the port power is actually being set to a slightly higher power. here is where I think there is most likely a type-o. in fact, it is probably a transposition. The label at the top should be -40 to -12 dBm and what is available at the source out (the label in the bottom) should be -42 to -13 because of the internal losses.
Hi Daras,
Thanks for the reply.
That would be much clear.
Thank you.
I went back and found the app note that this diagram came from and I think the problem is looking at the diagram out of context from the explanation that proceeds it (and also a bad case of proper labeling of the diagram). This section is describing a particular Gain Compression measurement setup where the author is trying to achieve a power sweep range of -10 to +18 dBm at the input to the DUT using a 34 dB Gain external amplifier. If you work backward, you see that the PNA source would have to be set to a power sweep of -44 to -16 dBm. However as you can see in the table right above this diagram the minimum source power with 0 dB attenuation is -27 dBm. So to achieve the desired power range, in this example, the author is setting the source step attenuator to 20 dB. So the power range label that you highlighted at the top of the diagram is the power setting in the UI for port 1, because in the PNA firmware the user sets the power level relative to the port and not relative to the source (i.e. the 20 dB attenuation is already included in the power setting). Now since there is additional path losses internally, to achieve -44 to -16, the port power is actually being set to a slightly higher power. here is where I think there is most likely a type-o. in fact, it is probably a transposition. The label at the top should be -40 to -12 dBm and what is available at the source out (the label in the bottom) should be -42 to -13 because of the internal losses.