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So for a basic little inverting amplifier using a 741 op amp, measured at frequencies of 10 Hz, 1000 Hz, and 100 kHz...
we might expect the gain to behave like the theoretical at 10 Hz and 1000 Hz but begin to be measured less than the theoretical at 100 kHz?
That's true for a gain of plus one. But since this thread started with a question about the frequency dependence of an inverting amp it should be noted that the BW = 500000/2 =250kHz for an inverting amp with a gain of minus one (as I noted in my previous post).For the 741 the GBW can be as low as 500kHz and the slew rate around 0.5 V/us, so for an input peak of 1v and gain of 1 we would have:
BW=GBW/G=500000/1=500kHz
No.As others have pointed out, there are better op amps out there including the low cost LM358 which work much better than the 741. The slew rate and GBW are roughly the same ....
That's true for a gain of plus one. But since this thread started with a question about the frequency dependence of an inverting amp it should be noted that the BW = 500000/2 =250kHz for an inverting amp with a gain of minus one (as I noted in my previous post).
No.
The LM358 dual opamp has exactly the same opamps as the LM324 quad opamp. They are low power so in addition to their horrible crossover distortion their slew rate is terrible.
Their datasheets don't even show how bad is their slew rate when they have an output near their max rail voltage.
I never implied that you do. I was just noting that, in your calculation for the BW you used a value of 1 for a gain of 1 and that's only true for a gain of plus 1 not minus 1. OK?Yeah, that's just not correct nor complete. You can never calculate the usable frequency on just the GBW alone.
I never implied that you do. I was just noting that, in your calculation for the BW you used a value of 1 for a gain of 1 and that's only true for a gain of plus 1 not minus 1. OK?
No, it's not a vague approximation. Read this.Hello there Carl,
Well i cant figure out where you got that idea from. It may be a little bit better for a gain of +1 with the output shorted to the inverting terminal (voltage follower) but it doesnt change THAT much when we set it up as an inverting amplifier with a gain of 1.
Where did you get that information from as it sounds like one of those vague approximations we run into now and then?
No, it's not a vague approximation. Read this.