Opa172 replaces lf357n

zewei lv

Other Parts Discussed in Thread: OPA172

Replace lf357n with opa172, and the output waveform is incorrect。Please help me ！Thanks！

Error waveform Correct waveform

0 zewei lv over 3 years ago

picture 4 is right .picture 3 is wrong.

0 kai klaas69 over 3 years ago

Guru 140200 points

Hi Zewei,

the LF357 is a decompensated OPAmp and is much faster than the OPA172.

Kai

0 Ron Michallick over 3 years ago in reply to zewei lv

Hello Zewei.

The AC gain looks like 1M/100 = 10,000. It would be better to get this gain in two stages.

The input is small and the edges are steep. Try a faster op amp.

0 kai klaas69 over 3 years ago

Guru 140200 points

Hi Zewei,

what is the input signal (amplitude, offset, timing)? What is the supply voltage?

Kai

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