What is Group Delay?

All frequency components of a signal are delayed when they pass though a filter. Group delay in a filter is the time delay of the signal through the device under test as a function of frequency. If we take the example of a modulated sine wave, for example an AM radio signal. Group delay is a measurement of the time taken by the modulated signal to get through the system.

Group Delay is measured in seconds.

For an ideal filter, the phase will be linear and the group delay would be constant. However, in the real world group delay distortions occur, as signals at different frequencies take different amounts of time to pass through a filter.