Post Go back to editing

# AD9645 : usage of S-Parameter file

Hello,

This file is not a S-Parameter but a calculation tool to see input impedance.
I'd like to confirm how to use this.
In the AD9645_AINDIFFZ" tab , "R-Math" cell and "jX-Math" cell will be set and then it calculate series resistance and series capacitance, I understood it. (Simaltanously parallel resistance and parallel capacitance are calculated)

Q1. I think the  "R-Math" and "jX-Math" are external parts for AD9645 input terminal. Is it correct my understanding ?

Q2. AD9645 has a differential Input, so the series resistance are two like as "R" in figure 11 of the datasheet(Ref.C). The "R-Math" shoul be input the double value of "R" ?

Best regards,

y_suzuki

Parents
• 2. Use the parallel impedance model

• Hello UmeshJ,

I read the article which you mentioned and I understood, I think.
I think the "AD9645_S-Parameter.xls" file is a solution for mathematical approach.

Our customer wants to us to explain how to use the "AD9645_S-Parameter.xls"
So I'd like to know the input parameter of "AD9645_S-Parameter.xls".
I marked two parameter in the attached figure file. I think these two parameters are should be set by user.
I think the "40" means resistance and "3.50E-12" means capacitance.
But I could not confirm where should I refer about these parameter.

1. What parameter should input to "40"'s cell ? Does this resistance mean the external input resister to dump return spike ?

2. This "3.5E-12", Is this a value referenced  input differential capacitance(3.5pF) in the datasheet ?

Best regards,

y_suzuki

• Series means each VIN+ or VIN- pin will have R and jX components in series to GND.

Parallel means the R and C will appear across VIN+/VIN- pins. this is more straightforward and is listed in the datasheet. • Hello UmeshJ,