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strange sine wave

pccmd

Jul 28, 2009
8
Joined
Jul 28, 2009
Messages
8
Good Day.
I have attached dual trace in which upper is from first op amp stage(square wave) and lower is second stage output, supposedly a sine wave. The design from National Semi. calls for a high speed, low noise op amp lmh6622 and 1% resistors, but I used 1458 I have already and common 5% resistors and cheapo capacitors. Supply +9v and -9v both checked.

So the questions:
1) could all that be why the waveforms are asymmetric relative to X-axis, and why the duration of (+) and (-) portions are so unequal?
2) what's with the notch in lower trace corresponding to where the "square wave" goes (-) ?

Thanks for assistance and I hope I haven't exasperated anyone with this posting.

CC
 

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neon

Oct 21, 2006
1,325
Joined
Oct 21, 2006
Messages
1,325
it looks fine to me except ther amplifier has serious rail problems. fix that first. then you may see a not so simetrical sinewave.
 
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