Op-amp input capacitance

[George]

Hello,

Is there any way to estimate the input capacitance of an op-amp (say the
TL082) in unity gain, voltage follower mode? A friend estimates it as
about 12 pF based on some transient voltage lab tests. I couldn't find
any info about this on the TI data sheets, unless I missed it.

Also, does the Pspice op-amp model for the TL082 include input
capacitance? My guess is that is does not.

George

 

[Jim Thompson]

Hello,

Is there any way to estimate the input capacitance of an op-amp (say the
TL082) in unity gain, voltage follower mode? A friend estimates it as
about 12 pF based on some transient voltage lab tests. I couldn't find
any info about this on the TI data sheets, unless I missed it.

Also, does the Pspice op-amp model for the TL082 include input
capacitance? My guess is that is does not.

George

If it's a DIP, it's about 4pF per pin... almost all of it package
related, NOT on the chip itself... chip pad is probably ~100fF.

...Jim Thompson

 

[George]

If it's a DIP, it's about 4pF per pin... almost all of it package
related, NOT on the chip itself... chip pad is probably ~100fF.

...Jim Thompson

It's a DIP. The 4 pF sounds reasonable. Thanks for the info.

George