Question

When a differential amplifier is operated single-ended.
A) The output is grounded.
B) One input is grounded and signal is applied to the other.
C) Both inputs are connected together.
D) The output is not inverted.

Answer 1

Hint: We need to understand the operational conditions of the operational amplifiers, its conditions when the amplifier has to be grounded and the points which should be grounded in order to get the required output. These can be used to solve this problem.

Complete Solution Step-by-Step:
A differential amplifier is a semiconductor device which has two terminals of input and output each. The voltage supplied to the input terminals are amplified and comes as output through the output terminals.
The differential operational amplifiers are of different types. Among them, one is the single-ended operational amplifiers. In this type of the amplifier an input voltage is given to one of the terminals and the other terminal is grounded to get the required amplification across the output terminals.
The voltage gain across the two output terminals is such that they have the same magnitude, but they are out-of-phase with respect to each of them.

We are asked about the differential operational amplifiers which use this single-ended mode of operation. When a signal V is given to the terminal 1 and the terminal 2 is grounded, we get an output across both the output terminals. The $$V_{O3}$$ across the terminal 3 will be out of phase with the V and the $$V_{O4}$$ across the terminal 4 will be in phase with the V, though both of them have the same amplitude.

Hence, the correct answer is option B.

Note:
The differential operational amplifiers are of two types. One is the single ended amplifier and the other is the common mode amplifiers. In the common mode, signal is provided at both the input terminals and the output is the resultant of these input voltages.