Signals and Systems

4.18 STEP RESPONSE OF SERIES R–C CIRCUIT

Figure 4.22 shows a R–C circuit. The capacitance of the circuit has initial charge Q₀ such that it opposes the flow of charging current. Let the switch K be closed at t = 0.

 

 

Fig. 4.22 RC series circuit

 

The circuit equation in time domain is given by

 

 

The Laplace transform of Eq. (4.79) is given by

 

 

In the above equation, the term i(0–) represent the initial current of the circuit such that ...