# What does 'passband phase' and 'stopband phase' mean?

I've been provided with a Bode plot for an RC filter circuit with a cutoff frequency of 10kHz. Im asked to find the stopband and passband phase from the graph. I'm confused how these can be just a single number, since stopband and passband represent a range of frequencies. (All the frequencies that can pass through the filter and all the frequencies that would be attenuated).

So when giving the stopband or passband phase, should it be the first value of phase in each band? The last value? Maybe a range of values? Or possibly the difference between the first and last values (i.e. how long the band lasts in phase)?

If anyone can help me clear this up I'd appreciate it

• I'm confused how these can be just a single number - I share your confusion - they cannot be a single number. Apr 23, 2020 at 10:26
• @Andyaka so do you think I should write it as a range of values?, e.g. x radians to y radians Apr 23, 2020 at 10:52
• Maybe you need to describe what the phase is doing if it's not constant. The exact numerical values aren't important, they'll change for any given filter. What is important is the overall behaviour. Is the phase approaching any constant value in either of those regions? Is the phase approximately linear in either of those regions? Does it change rapidly anywhere? How about you provide us in your post with the Bode plot you've been provided with? Apr 23, 2020 at 10:52
• @Neil_UK I don't have a digital copy of the Bode plot unfortunately, but I don't think its asking for what the phase is doing. The actual syntax of the question is "What is the passband phase in radians:" Then it gives a space to answer: "θpass-actual = ......" Apr 23, 2020 at 10:55