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Operational Amplifier

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Anusha_dhananjaya

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HI ;-)
I was going through op-amp.... I have certain doubts.....
1) Concept of virtual ground
2) Output swing
can anybody please answer this:cry:..... thanks a lot in advance :smile:
 

Thanks a lot... I am a beginner.. Op amp is in my syllabus..... I will consider ur advise thanks :)
 

You can donwload a book from Texas Instruments for free that is quite good: Op Amps for Everyone by Ron Mancini

**broken link removed**

Please have a look at sections
3.3 The Inverting Op Amp (contains a short explanation of virtual ground) and
11.3.5 Maximum Output Voltage Swing
 

Read some simple texts first....
 

I/p impedance of an opamp is very high and hence very little current flows thru it's inputs and hence very little voltage drop occurs at i/p.Hence if one of it's i/p is grounded ,since voltage difference b/w two i/ps will be very less we can assume other one of the i/p also to be at ground and hence giving rise o term 'virtual gound'.
 

sadmax said:
I/p impedance of an opamp is very high and hence very little current flows thru it's inputs and hence very little voltage drop occurs at i/p.Hence if one of it's i/p is grounded ,since voltage difference b/w two i/ps will be very less we can assume other one of the i/p also to be at ground and hence giving rise o term 'virtual gound'.
Click to expand...

The high input impedance of the opamp inputs is NOT the reason for the "virtual ground concept". Remember: This concept applies also to the Current-feedback topology with a very low negative input impedance.
The background is the very high loop gain that very often can be assumed to approach infinity.
 

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