The correct answer is: A. Converts AC signal from low frequency to high frequency.
A chopper amplifier is a type of amplifier that converts an AC signal from a low frequency to a high frequency. This is done by chopping the AC signal into a series of pulses, which are then amplified by a high-frequency amplifier. The amplified pulses are then re-assembled into the original AC signal.
Chopper amplifiers are used in a variety of applications, including power supplies, audio amplifiers, and data acquisition systems. They are also used in some types of sensors, such as accelerometers and gyroscopes.
Option B is incorrect because a chopper amplifier does not convert a DC signal from low frequency to high frequency. A DC signal is a signal that has a constant value, and a chopper amplifier cannot change the value of a signal.
Option C is incorrect because a chopper amplifier does not convert an AC signal from low frequency to DC high frequency. A DC signal is a signal that has a constant value, and a chopper amplifier cannot change the value of a signal.
Option D is incorrect because a chopper amplifier does not convert a DC signal from low frequency to high frequency. A DC signal is a signal that has a constant value, and a chopper amplifier cannot change the value of a signal.