why the gain of

[zhi_yi]

hi there, please tell me, why the gain of operational amplifier is very high? is it because of the circuit inside it have many stage of amplifier? for example inside 741 have many stage of class A amplifiers and class B amplifier, like differential amplifier and then follow by cascade amplifier, etc, so the output gain of the operational amplifiers is very high, is it true?

 

[chemelec]

The "Open Loop Gain" is High.

But when you use an Opamp, you determine the actual gain with a feedback resistor. The actual gain you determine may not be very high.

 

[bloki]

From the theory, shortly: the operational amplifier is differential amplifier with infinite gain and infinite input impedance. Classic op amps have gain about 200.000 and about 1Meg input impedance like 741.
All what is inside the chip is matter of design.

 

[zhi_yi]

quote :
From the theory, shortly: the operational amplifier is differential amplifier with infinite gain and infinite input impedance. Classic op amps have gain about 200.000 and about 1Meg input impedance like 741.
All what is inside the chip is matter of design.

so the gain is high because of it's design? sometime ago i saw a schematic, it said that the schematic is the schematic inside the 741, it has many stage of amplifier, like differential amplifier, etc, so, i thought that the gain is high because it has many stage of amplifier inside the operational amplifier.. okay.. thank you for the reply

 

[Roff]

I believe most op amps have two internal gain stages, plus a unity gain follower to provide low output impedance. Transconductance amplifiers omit the unity gain follower.