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Measurements >> RF Measurements >> Active-Balun Characterization of NF
https://designers-guide.org/forum/YaBB.pl?num=1240201234

Message started by aaron_do on Apr 19^th, 2009, 9:20pm

Title: Active-Balun Characterization of NF
Post by aaron_do on Apr 19^th, 2009, 9:20pm

Hi all,

I have an active balun which I want to characterize using on-wafer probing. Unfortunately, i'm not sure how I would go about calibrating the system for NF/conversion gain measurement. Does anybody have any good ideas? Keep in mind that the system needs to have single ended input and differential outputs.

I can see 2 possibilities.

1) calibrate the system in GSG_in GSG_out configuration. The actual output is GSSG with an off chip balun (to combine the signals). Measure the NF. I would then have to live with the inaccuracy of the measurement.

2) Calibrate the system in GSG_in GSG_out configuration. Terminate one of the output ports (either plus or minus) in 50 ohms. Measure the NF from GSG_in to the other output port. Correct the measurement (due to noise correlation/lack of).

Which one is better, or are there any other ways?

thanks,
Aaron

Title: Re: Active-Balun Characterization of NF
Post by pancho_hideboo on Apr 20^th, 2009, 6:44am

Measure losses in the following two cases.
(1) "GSG"-"Thru"-"GSG"
(2) "180degHyb"="GSSG"="Thru"="GSSG"="180degHyb"

Measure DUT like following.
"GSG"-"DUT"="GSSG"="180degHyb"

Here use half of loss (1) as "Pre loss Compensation".
And use half of loss (2) as "Post loss Compensation".
You can use frequency table for both "Pre loss Compensation" and "Post loss Compensation" as well as fixed values.

See the following.
http://www.designers-guide.org/Forum/YaBB.pl?num=1233236788/1#1

Title: Re: Active-Balun Characterization of NF
Post by aaron_do on Apr 20^th, 2009, 7:04am

Thanks. That sounds more reasonable.