In SISO(Single Input Single output) cases, My professor keeps mentioning the speed of response and crossover frequency interchangeably. I don't really understand what the speed of response means also ? Does higher speed of response mean lower transient time? Also what is the relationship between crossover frequency and speed of response? I am aware that the crossover frequency is when gain is 0db on bode plot

  • \$\begingroup\$ Typically cutoff is at the -3 dB mark. \$\endgroup\$ – schadjo Mar 27 '18 at 19:48
  • \$\begingroup\$ Firstly be careful when using abbreviations be careful as they may not always be obvious to everybody. I'm guessing 'SISO' is referring to a Single Input Single output control loops. Secondly provide the context with a specific example and your thoughts. We are happy to help but your professor isn't interested in how clever we are. Hint: what happens if you take a simple RC low-pass filter and reduce its corner frequency. How does this affect the output voltage ability to follow the input. This isn't a control loop but should provide some insight. \$\endgroup\$ – Warren Hill Mar 27 '18 at 19:54
  • \$\begingroup\$ I made a mistake between cutoff and cross over , sorry \$\endgroup\$ – aadil095 Mar 27 '18 at 19:55
  • \$\begingroup\$ Crossover frequency is proportional to the time constant \$\tau\$ in a step response ( en.wikipedia.org/wiki/Step_response#With_one_dominant_pole ). But low-frequency gain \$A_0\$, and feedback factor \$\beta\$ are also important factors. \$\endgroup\$ – HKOB Mar 27 '18 at 21:11
  • \$\begingroup\$ \$\omega_c=1/\tau\$ for a 1st order TF. What course are you doing that deals with quite advanced control topics (in other posts) and yet you haven't covered basic 1st order concepts? \$\endgroup\$ – Chu Mar 27 '18 at 22:23

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