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problem with op37 response

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saurabh17g

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We are using Op37 opamp to amplify the output of AD9833(frequency generator). We have built a non inverting configuration and the gain is 5(Rf=220k and Rin = 56k).
Our expectation is that this gain should be constant from 1Hz to 1MHz. But after 300Khz, we are finding getting sudden amplification and the output appears as clipped sine wave.
This behavior continues till 1MHz and we get a sine wave at 1MHz with distorted (almost triangular) shape.

GBW of Op37 = 63MHz. According to datasheet.
So theoretically,
it should give gain of 9 at 8MHz as well!
 

karesz

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saurabh17g said:
...GBW of Op37 = 63MHz. According to datasheet...
Hi,
Or even less, refer pls to page 2 of datasheet:
at F0 10KHz is min 45, typ 63MHz, but
at F0 1MHz is typ 40MHz...
And all these maybe at 2KOhm load (Signal level & load are not clearly declared).
K.
 

LvW

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Quote:
This behavior continues till 1MHz and we get a sine wave at 1MHz with distorted (almost triangular) shape.

The triangular shape indicates slew rate influence. Try smaller input amplitudes.
By the way, specified values are confirmed by the data sheet for closed-loop gain values larger than 5. So you are at the lower limit.
 

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