What is the cutoff frequency of a filter where the output drops to 70.7% of its maximum value?

The cutoff frequency of a filter is defined as the frequency at which the output signal has dropped to 70.7% (or -3 dB) of its maximum amplitude in relation to the input signal. This point is critical because it indicates where the filter begins to attenuate higher or lower frequencies, depending on whether it is a low-pass or high-pass filter. In the context of electronic filtering, understanding the cutoff frequency is essential for designing systems that require specific frequency response characteristics.

The significance of the 70.7% value stems from the relationship between voltage and power in electrical systems. When you drop to 70.7% of the maximum output voltage, you effectively see a 3 dB reduction in power, which is an industry-standard reference point for determining filter performance.

The other terms, while related to frequency response and filter behavior, do not accurately describe this specific phenomenon. For example, crossover frequency typically refers to the frequency at which two different signals intersect or where the output of a filter shifts from one response region to another. Critical frequency might loosely refer to a specific point in the frequency response but does not have the standardized definition that cutoff frequency does. Quarter frequency might refer to a specific division in a frequency spectrum but is not