For testing spec OP AMP, can i use this circuit ?

[ammjy]

Hello !
i don't know about OP AMP well. but, for my project i buyed low noise op amp OP37G.
but, i don't know it's fake or not fake. so i want check my op amp via input bias current.
Please, see screenshot picture. can i use this circuit for checking spec OP37G ?
i have EEVBlog ucurrent.
in datasheet, input bias current is typical ±15 nA, Maximum ±80 nA.

and checking via input bias current is good method ?
i want check via offset voltage. but, my oscilloscope resolution is just 2mV with Bandwith limit. i don't have idea.\

Please, let me know. Please, i need help.

[Zero999]

You should use higher resistor values than that to measure the bias current.

Why are you using an oscilloscope to measure the offset current? It's the wrong tool for the job. You need a volt meter to measure DC voltages.

[ammjy]

Thanks you.

i mistake wrote, Sorry. i always in tension.....

i will use my multimeter and ucurrent. but, multimeter can't measure nV range. ucurrent is for currunt measure.

without any input, just with x1000 feedback circuit, can i measure offset voltage ? +/- 15~80 nV ?

[danadak]

From one of the gurus of our time -

https://www.ti.com/ww/en/bobpease/assets/www-national-com_rap.pdf

Pick the article "What's All This Femtoampere Stuff, Anyhow?" and "What's All This Teflon Stuff, Anyhow?"


Regards, Dana.

[b_force]

Why are you using an oscilloscope to measure the offset current? It's the wrong tool for the job. You need a volt meter to measure DC voltages.

That really depends on the type of scope and multimeter.
I know enough scopes that are much more accurate than some multimeters.

[Zero999]

Thanks you.

i mistake wrote, Sorry. i always in tension.....

i will use my multimeter and ucurrent. but, multimeter can't measure nV range. ucurrent is for currunt measure.

without any input, just with x1000 feedback circuit, can i measure offset voltage ? +/- 15~80 nV ?

It depends on the accuracy of the multimeter. You may need to increase the gain further.

Why are you using an oscilloscope to measure the offset current? It's the wrong tool for the job. You need a volt meter to measure DC voltages.

That really depends on the type of scope and multimeter.
I know enough scopes that are much more accurate than some multimeters.

They must be pretty poor multimeterss.

[ammjy]

From one of the gurus of our time -

https://www.ti.com/ww/en/bobpease/assets/www-national-com_rap.pdf

Pick the article "What's All This Femtoampere Stuff, Anyhow?" and "What's All This Teflon Stuff, Anyhow?"


Regards, Dana.

Thanks you teach me.

I'll not forgot your help. Thanks !

[ammjy]

Thanks you.

i mistake wrote, Sorry. i always in tension.....

i will use my multimeter and ucurrent. but, multimeter can't measure nV range. ucurrent is for currunt measure.

without any input, just with x1000 feedback circuit, can i measure offset voltage ? +/- 15~80 nV ?

It depends on the accuracy of the multimeter. You may need to increase the gain further.

Why are you using an oscilloscope to measure the offset current? It's the wrong tool for the job. You need a volt meter to measure DC voltages.

That really depends on the type of scope and multimeter.
I know enough scopes that are much more accurate than some multimeters.

They must be pretty poor multimeterss.

Thanks you, your advice.
i'll not forgot your help ! ill try !

[ammjy]

Why are you using an oscilloscope to measure the offset current? It's the wrong tool for the job. You need a volt meter to measure DC voltages.

That really depends on the type of scope and multimeter.
I know enough scopes that are much more accurate than some multimeters.

Thanks you comment !
today, i studied via you.