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Topic: OpAmp Freq and Slew rate? (Read 531 times) previous topic - next topic

louarnold

It is correct that an opamp with lower bandwidth will reproduce a signal with a low peak input voltage - say 125mV. Where as if I have a 5V peak signal, i would need a much higher slew rate? Slew rate= (2*pi*F*Vpk/1e-6)[V/us]

I have an signal source that gives me  5V peak, 68Mhz square wave at a very low output impedance. I wanted a buffer op amp to help interface it to other things. If I use a fraction of the input voltage, that requires a lower slew rate and I can get away with a lower bandwidth op-amp. Is that correct?

vasquo

Here's the typical relationship between Vpeak and SR and frequency.

Area above diagonal line = good.


> I wanted a buffer op amp to help interface it to other things.

Why not just use a high-speed logic line driver (non-inverting)?  Example CD74HCT241

Docedison

Excellent sugestion... One more thing, Tie the unused inputs low (to ground) the unused buffers can oscillate and when that happens the gates involved draw a great deal of current from the 5V power supply and get quiite hot.

Bob
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