Which among the following amplifier circuit exhibit the output voltage in the form of phase inversion ?

Which among the following amplifier circuit exhibit the output voltage in the form of phase inversion ?

a. Adder
b. Substractor
c. Integrator
d. Differentiator

Correct Answer : a. Adder

Explanation :

In any adder circuitry of Op-amp, the output voltage must be equivalent to the summation of all input voltages where each input voltage is a multiple of constant gain factor. This circuit is usually more similar to inverting scalar type of amplifier with an exception of possessing more than one input. Therefore, output voltage of adder or summer Op-amp is phase inverted .
Referring to subtractor, integrator and differentiator amplifiers, the output voltage of subtractor deals with the difference between two input signals, while integrator generates its output voltage in terms of integral of input voltage whereas the output voltage of differentiator is proportional to change in input in accordance to time.