Electronics Engineering (ELEX) Board Practice Exam

In signal processing, what type of filter is designed to only allow a certain range of frequencies to pass?

1. Low-pass filter

2. High-pass filter

3. Band pass filter

4. Notch filter

The correct answer is: Band pass filter

In signal processing, a band pass filter is specifically designed to allow a certain range of frequencies to pass while attenuating frequencies outside that range. This type of filter effectively blocks both low frequencies below the passband and high frequencies above the passband, thereby isolating and allowing only the desired range of signal frequencies. Band pass filters are crucial in applications such as audio processing, communications, and various electronic systems where isolating a specific frequency band from a broader spectrum is necessary for clarity or function. They can be implemented using a combination of both low-pass and high-pass filters, enabling flexibility in the design of the frequency response characteristics based on the application needs. In contrast, low-pass filters permit frequencies below a specified cutoff frequency to pass while attenuating higher frequencies, and high-pass filters do the opposite by allowing higher frequencies to pass while blocking lower frequencies. Notch filters, meanwhile, are designed to suppress a very narrow band of frequencies rather than allowing a range to pass through.