Ask some questions about amplifier application

user4768469

Intellectual 290 points

Hi,

As you know, for an amplifier, the full power bandwidth F_MAX = (Slew Rate)/2πVpk, we get this formula assuming that the input signa is sinewave. In other case, If the input signal is square wave, triangular wave, and other arbitrary wave, how to calculate the full power bandwidth?
For an amplifier, the signal rise time tr=0.35/BW, I want to know how to derive this formula?

Thanks!

over 5 years ago

0 Michael Steffes over 5 years ago

Guru 48395 points

Actually that FPBW equation you report is a long running error in the industry. Since you are measuring at -3dB down, you need to reduce the Vpeak by 0.707 to get a more accurate result. But it is still normally only approximate,

dealt with some of this recently in these two articles.

https://www.planetanalog.com/separating-linear-from-slew-limited-performance-in-amplifiers-part-1-of-2-the-signal-sped-up-insight-14/

https://www.planetanalog.com/separating-linear-from-slew-limited-performance-in-high-speed-amplifiers-part-2-of-2-the-signal-sped-up-insight-15/

0 kai klaas69 over 5 years ago

Guru 140200 points

Hi,

your question is a bit a contradiction in itself because square waves and triangular waves have an infinite number of harmonics without any bandwidth limit. Because of this no amplifier is able to truly reproduce a square wave or trinagular wave at its output, and this the less the higher the fundamental frequency is.

Kai

Amplifiers

Amplifiers forum

Ask some questions about amplifier application