0195136047.pdf

168 TIME-DEPENDENT CIRCUIT ANALYSIS

G 0

R C

H

(b)

Σ

+

+

+

−

GA = G 1 G 2 G 3 Σ

Figure E3.4.4Continued

G 0

C

R

(c)

+

+Σ

GA

1 + GAH

RC

(d)

GA

G 0 + 1 + GAH

Solution

The three blocks in cascade are combined to yieldGA =G 1 G 2 G 3 , as illustrated in Figure

E3.4.4(b).

By eliminating the feedback path, the circuit of Figure E3.4.4(c) is obtained. By eliminating

the auxiliary forward path, one gets the circuit of Figure E3.4.4(d). Thus,

C

R

=G 0 +

GA

1 +GAH

whereGA=G 1 G 2 G 3.

A linear system of equations can also be represented diagrammatically by asignal-flow graph

(consisting of nodes and branches), which is used to describe a system schematically in terms of

its constituent parts. However, in view of the scope of this text, the topic of signal-flow graph is

not presented.

3.5 COMPUTER-AIDED CIRCUIT SIMULATION FOR TRANSIENT ANALYSIS, AC

ANALYSIS, AND FREQUENCY RESPONSE USING PSPICE AND PROBE

Transient Analysis

PSpice is capable of performing transient circuit analysis, for which the request is given by the

following statement:

• TRAN TSTEP TSTOP TSTART TMAX UIC
  where TSTEP is the interval between points printed, plotted, or reported to PROBE, TSTOP
  is the time value for which the analysis is stopped, TSTART is the beginning time value for