The correct answer is:
(b) FM modulators
Explanation:
A differentiator circuit is often used in applications where a signal's rate of change is of interest, such as:
- FM Modulators: Differentiator circuits are used in Frequency Modulation (FM) systems. In FM, the frequency of the carrier signal is varied in proportion to the input signal. The differentiator generates a signal that is proportional to the rate of change of the input, which is essential for FM modulation.
The other options do not typically use differentiator circuits in the same way:
- (c) Wave generators: Wave generators often use oscillators, not differentiators, to produce periodic waveforms.
- (d) Frequency Shift Keying (FSK): While FSK involves varying the frequency of a signal to represent data, differentiators are not directly used in the core FSK process. FSK uses frequency modulation or demodulation techniques that may involve other types of circuits.
Therefore, the correct application is FM modulation, which uses a differentiator to convert the input signal into a frequency-modulated output.