[LMC6772-Q1] about input impedance

Paul Kim

Intellectual 1430 points

Other Parts Discussed in Thread: LMC6772-Q1

Hi team

i like to know LMC6772-Q1's input impedance at VCC = 5V.

i saw 0.04 pA input current at VCC = 5V.

LMC6772-Q1's input impedance at VCC = 5V is 125 GOhm = 5V/0.04 pA, right ?

over 7 years ago

0 Daniel Hartung over 7 years ago

TI__Mastermind 21965 points

Hi Paul,

You are correct that you can get an input impedance of the part like that. It is important to note that will give the typical input impedance since that is the typical output current.

Thanks,

Daniel

0 Paul Grohe over 7 years ago

TI__Mastermind 49896 points

Hi Paul,

The correct way is to use the change in Vcm over the change in bias current.

So looking at the above curve, it's roughly +20fA at 1V, and -30fA at 4V.

(1-4V) / (+20fA - (-30fA)) = 3V/50fA = 60TOhms

Regards,

Amplifiers

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[LMC6772-Q1] about input impedance