AN 669: Drive-On-Chip Design Example for Cyclone V Devices

ID 683466
Date 5/15/2022
Public
Document Table of Contents

9.10.5. IIR Filter Tuning Parameters

Table 21.  IIR Filter Tuning Parameters
Parameter Description
Ωd Corner frequency (rad/s) above which the denominator response magnitude begins to decrease.
ζd Damping factor that determines the sharpness of the corner at Ωd; ζd < sqrt(0.5) results in a filter response peak (filter resonance) around Ωd, whereas ζd > sqrt(0.5) gives a more gradual (more strongly damped) transition with no peak.
Ωn Corner frequency (rad/s) above which the numerator response magnitude begins to increase.
ζn Damping factor that determines the sharpness of the corner at Ωn; ζn < sqrt(0.5) results in a filter response trough around Ωn, whereas ζn > sqrt(0.5) gives a more gradual transition with no trough.

Use these four parameters to create different filter response shapes. For vibration suppression, use a notch characteristic to decrease the system gain only around the frequency of interest. Set Ωn = Ωd and ζn < ζd. The gain at Ωn = Ωd is then equal to 
ζn/ ζd