Virtual ground concept of Op-amp with negative feedback
Q. Why do the virtual ground strategy is adopted in case of Op-amps with negative feedback mechanism corresponding to the below figure?
- Published on 26 Oct 15a. Due to reduction in an input voltage at inverting terminal to zero
b. Due to reduction in an input voltage at inverting terminal to unity
c. Due to increase in an input voltage at inverting terminal greater than unity
d. All of the above
ANSWER: Due to reduction in an input voltage at inverting terminal to zero
The notion of virtual ground originates from the condition when input voltage at the inverting terminal is insisted to reach a very minute value approximately to almost zero value. Thus, the point at which inverting terminal find its connection is significantly at the ground voltage and therefore, it is regarded at the virtual ground level. The reason behind getting reduction of input voltage to zero is the positive potential attained by point A and existence of the output voltage at the same time. Again, some part of output is fed back to input terminal out of phase. However, the sum of these two voltages become equal to zero.
