I have just learned about amplifier but the term infinite bandwidth confuses me a lot.plesse explain with some example.
What is meaning of infinite bandwidth of an amplifier
amplifierbandwidth
Related Solutions
An ideal digital signal has infinitely steep edges. We can compose this signal from sines, one fundamental and a number of harmonics.
Neither of those separate sines has infinite steepness. The only way to get our steep edge is by adding an infinite number of harmonics.
In some cases it works out to be more convenient. Some things (like human perception of pitch, and filter responses) respond to frequency logarithmically. That is, higher frequency octaves have more bandwidth than low frequency octaves.
It's the same reason low-pass or high-pass filter topologies have their roll-off described in dB/octave rather than dB/Hz. For example, we know that all first-order filters have a roll-off of 6dB/octave. This holds if we are designing a filter for 1kHz or 1GHz.
The same sort of issue applies to band-pass and band-reject filters. If we took a band-pass filter 100Hz wide at 1kHz, then scaled all the component values to move it up to 1GHz, then its bandwidth would be 100MHz. However, it would have the same fractional bandwidth.
Thus, it's convenient to specify the bandwidth of a particular topology as a fractional bandwidth because it does not change as the passband is moved by scaling all the component values.
Best Answer
An amplifier with infinite bandwidth would be able to reproduce any input, no matter how fast it changes. Even if the input were a 100 terahertz sine wave, or had steps from 1 V to 10 V in a fraction of a femtosecond, the amplifier would be able to reproduce that signal (scaled) at the output.
But this is an idealization...real amplifiers have limitted bandwidth, meaning that as the input signal increases in frequency, the output will not reproduce the input accurately. Furthermore, once feedback is added, the bandwidth of the amplifier circuit depends on the gain of the complete circuit.
Really fast op-amps on the market today have a "gain-bandwidth product" on the order or 1 or 2 GHz, but values for this parameter range from kilohertz up. A 10 MHz (GBW) op-amp, at gain of 1 (if it's unity-gain stable) can pass signals up to 10 MHz with low attenuation. Configured with feedback gain of 10, a 10 MHz op-amp could amplifiy signals up to 1 MHz, etc.
There is also an effect called slew rate limiting, separate from bandwidth, that limits the d/dt of the output voltage of an op-amp. This can produce distortion on step-shaped inputs, especially for high amplitudes, even when the bandwidth limitation implies that good reproduction is possible.