LMH6553: Output Impedance

Hi Ken,

I will check with the design team.

Best,

Sam

Hi Ken,

It looks like there may indeed be an issue with the plot, I'm going to have to investigate further.

Best,
Sam

Thanks Sam, I look forward to your findings.

BR, Ken

Hi,

this is very probably a scaling error on the coordinate axes. This can be seen very often in datasheets.

Kai

Hi Kai,

Yes that is what I suspected as well, which was my reason for asking this question. We need to know what is the actual output impedance.

BR, Ken

I will look into the scaling but may need to do some measurements to confirm.

Best,

Sam

Thanks Sam,

For now we have estimated that the output impedance is 10.8ohm at 200MHz from the simulation, but it would be good if you could confirm that.

BR, Ken

Hi Ken,

Thanks for the estimate. I'll try to have an answer for you as soon as possible.

Best,

Sam

Just confirming model revision, the TINA V9 has a model from 2008, the web folder shows a Pspice model but no TINA reference design - however that file is the same as the TINA file it seems, no mention of output impedance in modeled parameters - this quite old model would have come from the Ft. Collins national semi group - they may have missed this parameter, 

Thanks Michael, 

Yes, that is the model I was using and was only for a rough estimate. 10.8ohms seems more realistic than 300ohms at 200MHz, but I understand that it may not be the actual value.

BR, Ken

Hi Ken,

I'll be taking some measurements today, please standby.

Best,

Sam

Hi Sam,

How did it go?

Thanks, Ken

That seems quite a lot more reasonable Sam - going to update the erroneous one in the datasheet I am assuming. 

Hi Michael,

I agree, will put this in the queue.

Best,

Sam

Thanks Sam!

This really helps in understanding what is happening with our anti aliasing filter.

Best regards, Ken

Thank you for the clarification, Sam 

Kai