Which device can be used to suppress unwanted high-frequency harmonics?

A low-pass filter is a device specifically designed to allow signals with a frequency lower than a specified cutoff frequency to pass through while attenuating frequencies higher than that cutoff. This functionality makes it an effective tool for suppressing unwanted high-frequency harmonics that can interfere with the desired signal. By removing or reducing these high-frequency components, a low-pass filter helps to clean up the signal and enhance the overall signal quality.

In contrast, oscillators generate signals and are not used for frequency filtering. Phase discriminators measure phase differences between signals but do not directly filter frequencies, making them unsuitable for suppressing high-frequency harmonics. High-pass filters, on the other hand, allow high-frequency signals to pass while attenuating lower frequencies, which is the opposite of what is needed to suppress unwanted high-frequency harmonics. Therefore, the low-pass filter is the most appropriate choice for this application.