how to measure CMOS Transforer??

Paek Hyun · Oct 4, 2010

I have designed CMOS transformer for some RF circuits.
I can simulate transformer using MoM method. (in ADS)
but how can i measure CMOS transformer?
I want to know how different simulation and measure.

Transformer have a 6 port .. 2port output and 4port input
2:1x2 Transformer.

I want to get complete and exact S parameter for transformer.

so how to design transformer for measure and how can i measure?

BigBoss · Oct 4, 2010

You should prepare a test structure that has GSSG pads for each port of the transformer in according with your wafer test probes.Look at the mechanical specifications of your wafer test probe.
GSSG means Ground Signal Signal Ground.
Then you should prepare 2 structure for each measurement.One for S31 while Port-2 is terminated with 50Ohm on the wafer
The second one for S32 while Port-1 is terminated with 50 Ohm on the wafer.
But first of all, your must draw a calibration structure to calibrate your VNA.Calibration layout consists of Open,Short and 50 Ohm terminations. And you should repeat this calibration for each port.
After all these, you will have to de-embed the s-parameters of the test pads and lines from s-parameters of the transformer itself that is very difficult if the frequency is very high.
There are many tricks to measure passive component on the wafer.You may find some application docs. about these measurements..

Paek Hyun · Oct 5, 2010

hmm. I understand what you say.. but I have to use only GSG pad.
And I want to measure multiport over 6 port.
my transformer port have 6. These ports made of differential signal 4 port,output 1port, and ground. so GSSG pad wouldn't be measure my transformer.

I want to know not only probe station measure method.
in example, chip on board could be not use probe station. it could only use network analyzer.
(but I dont know de-embedding method.) and so on...

thank you for your concern and reply.
have a nice day.

BigBoss said:
You should prepare a test structure that has GSSG pads for each port of the transformer in according with your wafer test probes.Look at the mechanical specifications of your wafer test probe.
GSSG means Ground Signal Signal Ground.
Then you should prepare 2 structure for each measurement.One for S31 while Port-2 is terminated with 50Ohm on the wafer
The second one for S32 while Port-1 is terminated with 50 Ohm on the wafer.
But first of all, your must draw a calibration structure to calibrate your VNA.Calibration layout consists of Open,Short and 50 Ohm terminations. And you should repeat this calibration for each port.
After all these, you will have to de-embed the s-parameters of the test pads and lines from s-parameters of the transformer itself that is very difficult if the frequency is very high.
There are many tricks to measure passive component on the wafer.You may find some application docs. about these measurements..

how to measure CMOS Transforer??

Paek Hyun

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BigBoss

Advanced Member level 7

Paek Hyun

Paek Hyun

Newbie level 2

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how to measure CMOS Transforer??

Paek Hyun

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