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ADA4898 SPICE model input impedance

Question asked by alperen on Jun 19, 2017
Latest reply on Jun 20, 2017 by Gauzz

Hello,

I've been playing with ADA4898's SPICE model and I realized something about its input impedance. Here is the input section in .cir file of ADA4898

 

***Inputs***
S2 1 100 106 113 Switch
S3 9 101 106 113 Switch
VOS 1 2 dc 20e-6
IbiasP 110 2 dc -0.1e-6
IbiasN 110 9 dc -0.1e-6
RinCMP 110 2 Rideal 10e6 
RinCMN 9 110 Rideal 10e6
CinCMP 110 2 7e-12
CinCMN 9 110 7e-12
IOS 9 2 0.03e-6
RinDiff 9 2 Rideal 0.5e3
CinDiff 9 2 10e-12
*

*

Common mode resistance is modeled with a 10 MEG resistor, but the datasheet says 30 MEG input resistance. This is true for common mode and differential mode resistance and capacitance. The resistances are lower than what datasheet specifies and capacitances are higher. Are the modeled impedances represents the worst-case scenario?

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