# capacitor in series,is that Butterworth?

Now you all know the various analog filter types,Butterworth,Bessel,Chebychev...

My question is,if I put single capacitor in the signal path,it will block dc,acting like highpass filter,I believe its 6db per octave roll off.What type of filter that is? I want to imagine what kind of time domain transient response will it have,Bessel filter have less overshoot and post ringing than Butterworth,and I have no idea if my series capacitor is butterworth or bessel or maybe something else.

• Capacitor in series is single-pole high-pass RC filter. (Well, there's some resistance to ground somewhere, which provides the R.) – Nick Alexeev Apr 21 '17 at 2:02
• Who gave me the dislike and why? :( So as I understand it," single pole" is specific type of filter just like Butterworth or Bessel with its own unique transition band and impulse shape – wav scientist Apr 21 '17 at 3:20
• A single-pole filter is a single-pole filter, period. Butterworth, Bessel, Cheybyshev, etc, filters require multiple poles. – user207421 Apr 21 '17 at 4:57

$$1 / sqrt[ 1 + (Freq/Freq_3dB)^2]$$