Page 80 - Schaum's Outline of Theory and Problems of Electric Circuits

AMPLIFIERS AND OPERATIONAL AMPLIFIER CIRCUITS
CHAP. 5]
69
5 7=12 < t < 11=12
v o ¼
5ðsin 2 t 1=2Þ otherwise

Fig. 5-10

5
EXAMPLE 5.8 In Fig. 5-11, R 1 ¼ 10 k
, R 2 ¼ 50 k
, R i ¼ 500 k
, R o ¼ 0, and A ¼ 10 . Find v 2 =v 1 . Assume
the amplifier is not saturated.

Fig. 5-11

The sum of currents arriving at node B is zero. Note that v A ¼ 0 and v B ¼ v d . Therefore,

v 1 þ v d v d v 2 þ v d
þ þ ¼ 0 ð6Þ
10 500 50
Since R o ¼ 0, we have
5 5
v 2 ¼ Av d ¼ 10 v d or v d ¼ 10 v 2 ð7Þ