Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

virtual ground in OP AMP

Status
Not open for further replies.
rakesh_aadhimoolam

rakesh_aadhimoolam

Full Member level 4
Full Member level 4
Joined
Mar 14, 2006
Messages
206
Helped
19
Reputation
38
Reaction score
2
Trophy points
1,298
Activity points
2,751
virtual short op amp

i am electrical engg. i am new to this op-amp world. i would like to know what exactly a VIRTUAL GROUND refer to........


thanks
 

meaning of virtual ground in op amp

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'.
 

virtual ground ... there r two inputs to an Opamp now
whatever voltage is present at 1 input ...same is assumed to present at 2nd input too!
this concept is very vital ..
 


Ideal opamp gain is high. It makes the two input equal.If one input is connected to ground,the other is virtual ground
 

due to -ve feedback the -ve terminal approaches the +ve terminal since the gain of opamp is in 1000's .we say the -ve terminal of opamp is at virtual gnd (virtual since not really grounded)if +ve terminal is at gnd.
 
The op-amp has two input terminals. When the op-amp is used with some negative feedback around it, the two input terminals are at same potential [ideally], although they are physically not connected together. This is referred to as VIRTUAL SHORT [and NOT virtual ground]. In case one of the terminal is kept at GROUND Potential, then the other one is also at GROUND Potential. This can be referred to as VIRTUAL GROUND.
 

Both the inverting and non inverting inputs of an opamp are bootstrapped to each other. If one is set to a certian voltage the other input will follow......
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top