Op Amp Applications Handbook

SECTION 5-2

The Transfer Function

The S-Plane

Filters have a frequency dependent response because the impedance of a capacitor or an inductor changes with frequency. Therefore the complex impedances:

Eq.5-1

and

Eq.5-2

Eq.5-3

are used to describe the impedance of an inductor and a capacitor, respectively, where σ is the Neper frequency in nepers per second (NP/s) and ω is the angular frequency in radians per sec (rad/s).

By using standard circuit ...