Question

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

Answer 1

All the voltages are measured with respect to the ground voltage. The ground voltage is considered to be $0V$. As the name suggested, a single-ended differential amplifier amplifies the signal that is given through only one of the input.

Complete Step by step solution:
The inputs of a single ended differential amplifier are the ground on one end and signal on the other end.
Conventionally, we take the ground voltage $0V$ for each and every circuit. All the other voltages are measured with respect to ground voltage.
For example, the voltage in our houses is $220V$. This voltage is measured with respect to the ground only.

Thus, option (B) is the correct option.

Additional information: If we give two signals of different amplitudes to a differential amplifier, the difference of the amplitude will be amplified. For example, if one signal is $10V$and the other signal is $15V$ then $(15 - 10)V = 5V$will be amplified by the differential amplifier. In the case of a single ended differential amplifier, we have ground on one end and a signal $(8V)$ on the other end. We can say that on one end we have $0V$ and on the other end we have $8V$. Thus, $(8 - 0)V = 8V$ will be amplified. Thus we can treat a single-ended differential amplifier as any other differential amplifier with $0V$ as an input. So that the signal through the second input line gets amplified.

Note: If the output of such a differential amplifier is asked, the output can be easily calculated by treating a single ended differential amplifier like any other differential amplifier. The output will be the same in this case.