In the analysis of a passive 2nd order RC high pass filter, I find that the damping ratio zeta = 3/2 and the Quality Factor Q = 1/3. These values do not depend on R and C. I was under the impression that if the damping ratio is greater than one, then the system step response does not overshoot its steady state value. However, when performing step response in MATLAB to my system, I find that the circuit does overshoot slightly. I am analyzing the circuit below for equal R and C (10k and 100nF respectively).
I believe the calculations for zeta and Q to be correct, something must be wrong in my understanding of their role in the step response. Why does the circuit overshoot if it is "overdamped"?
I have repeated this procedure with a passive 2nd order RC LPF (same R and C values) and I do not see any overshoot. This agrees with my intuition. Why is the HPF different?
Thanks for any help that can be provided.