Confius about frequency...

what is f3db

I'm a little bit confius a lot of things about frequency!

1. If we design a simple amplifier, is f3dB or GBW(gain bandwith) is our frequency operation? It is the same with f0?

2. Is freq operation and freq response are the same?

3. f0 represent freq operation or freq response?

4. If we want to design a circuit which operates at 1.5GHz(example), which one will we consider?f3dB?GBW?freq operation?freq response?

5. Recently,I would like to use active inductor to my amplifier! In active inductor, they have self-resonant freq to ensure what is the inductance value at that freq! The question is,do I need to match the self-resonant freq of the activeL with the freq operation of the amp? If amp operates at 1.5GHz, the activeL should also have the self-resonant freq at 1.5GHz! Is that true?

Help mee...

guamak_menanak said:

I'm a little bit confius a lot of things about frequency!

1. If we design a simple amplifier, is f3dB or GBW(gain bandwith) is our frequency operation? It is the same with f0?

Click to expand...

Fo is usually the center frequency of a bandpass response. Gain-bandwidth product is a figure of merit of an active device. The F3db is the frequency where the gain is reduced by 3dB. Usually, you want to operate below this value.

If you operate over a bandwidth that is small compared to the frequency, in the old days you would use a tuned bandpass amplifier. On integrated circuits, this is not practical and you would use a broad band amplifier to save the inductors.