0195136047.pdf

PROBLEMS 383

+

−

500 kΩ

300 kΩ

i 2

i 1

10 V

Figure P7.2.13

−

+

8 mA

1

2

3

4

5

0

(b)

(a)

0.2 0.4 0.6 0.8 1

id, mA

2 V 500 Ω vd

+

−

id

500 Ω

vd, V

Figure P7.2.14

(c) The diode is to be represented by the model

of Figure 7.2.5(b) withVon = 0 .6 V and

Rf= 20 .

7.2.17Sketch the output waveform ofvo(t) in the circuit

shown in Figure P7.2.17 for the interval 0≤t≤

10 ms.

*7.2.18Consider the circuit shown in Figure P7.2.18 with
ideal diodes in order to approximate a two-
terminal nonlinear resistor whosev–icurve sat-
isfiesi= 0. 001 v^2 in a piecewise-linear fashion.

(a) Find the values ofR 1 ,R 2 , andR 3.

(b) Suppose that both diodes haveRf = 10 

andVon= 0 .5 V. Find the revised values of

the resistors and voltage sources (v 1 andv 2 )in

order to accomplish the same objective.

7.2.19Consider the small-signal operation of a diode

as represented in the model of Figure 7.2.5(b)

and thev–icurve given in Problem 7.2.14. Using

the circuit shown in Figure P7.2.19, develop an

approximate equation for the diode current.