Electronics > Beginners

Purpose of this amplifier circuit with op. amplifiers

(1/6) > >>

bonzer:
Hello everyone! Please help me to understand the main purpose behind such a configuration (see attached image).  What I see here is the formula of an amplifier with the gain from image gain.jpg attached. The request is to build a passband filter, so the gain I found is almost certainly right (but I'm not 100% sure). What surprises me the most is what goal made the creator to put them in that way? It feels like it could be a way to increase the open loop gain by putting a sequence of two so this way the gains get multiplied (in bode diagram it's the sum). I tried to build a block diagram to show what I mean.

NOTE: this circuit might be unstable and also uncomplete (so without compensation components or other additional stuff needed for big gain and so on).

Yansi:
Seems like some textbook schematic where there was too much (you know what) smoke present when writing the book?

Otherwise, it resembles a kind of PID regulator transfer function, but not really. Hard to tell what meaning it could have, when the context is not known.

bonzer:
Actually it is posted by a university professor so it still could only be a result of his imagination. Whatever, the circuit should be considered as a passband filter in my opinion (even though it says that it's an amplifier, but it's because the central frequency gain should be something like 34dB).

There's still some work to be done but if in your opinion (all you readers, not only Yansi) it's just a mind-scratching exercise then is my gain result 100% true (assuming op. amps are ideal) ? And what do you think about my block diagram?

Yansi:
I am used to different pass-band filters.  What advantages does this configuration have, above the common Sallen-key and MFB topologies?

I am just widely guessing, never seen this practically used anywhere.  :-//

edavid:
It appears to be a Wien Bridge filter, so do some reading about that.

Without knowing component values, it's hard to say.

BTW, in English we say "bandpass filter", not "passband filter".

Navigation

[0] Message Index

[#] Next page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod