0195136047.pdf

7.2 DIODES 349

WhenvD≥0orvS≥ 0 .6 V, the diode conducts. Once the diode conducts, the expression for

the load voltage can be obtained by the voltage divider rule, by considering that the ideal diode

behaves like a short circuit. The complete expression for the load voltage is therefore given by

vL=

10

10 + 1 + 0. 5

(vS− 0. 6 )= 8 .7 cosωt− 0. 52 , forvS≥ 0 .6V

andvL=0 forvS< 0 .6 V. The source and load voltages are sketched in Figure E7.2.4(c).

vS vL

v, V

5

0

− 5

− 10

10

0 0.0050.01 0.015 0.02 0.0250.03

(c)

t, s

10 Ω

(a)

1 Ω

−

+

+−

−

+

vL

vS

10 Ω vL

(b)

1 Ω

−

+

vS

v 1 +−

0.5 Ω 0.6 V

Ideal

diode

v 2

+vD− + −

−

+

Figure E7.2.4

EXAMPLE 7.2.5

Consider a forward-biased diode with a load resistance. Let the static volt–ampere characteristic
of the diode be given by Equations (7.2.1) and (7.2.2), and typically represented by Figure
7.2.4.

(a) For a dc bias voltageVB, obtain the load-line equation and the operating (quiescent) point