ABSTRACT
This chapter deals with the amplifiers' behavior when the frequency approaches and even passes the low extreme of the operational frequency band. Usually, the amplifier's frequency dependent behavior at low frequencies is caused by the coupling and bypass capacitors, and the amplifier's bandwidth is limited at high frequencies by the transistors' parasitic capacitances. Each capacitor has a region of activity in the frequency domain, which starts from "where it comes out of the open circuit state" to "where it enters the short circuit state." The classic approach to analyze an amplifier at low frequencies is similar to the AC analysis methods explained earlier except the external capacitors are not replaced by short circuits. The low-frequency inspection method is a straightforward approach to determine all the zeros and poles individually, without manipulating big fractional transfer functions.
