PROBLEMS 381that would yieldI=− 8 μA.
7.2.4A silicon diode is forward-biased withV= 0. 5
V at a temperature of 293 K. If the diode current
is 10 mA, calculate the saturation current of the
diode.
7.2.5WithV =50 mV, a certain diode at room tem-
perature is found to haveI= 16 μA and satisfies
I=IS(e^40 V− 1 ). Find the corresponding diffu-
sion current.
7.2.6A diode is connected in series with a voltage
source of 5 V and a resistance of 1 k. The
diode’s saturation current is given to be 10−^12
A and theI–Vcurve is shown in Figure P7.2.6.
Find the current through the diode in the circuit
by graphical analysis.
7.2.7For the circuit in Figure P7.2.7(a), determine the
currenti, given thei–vcurve of the diode shown
in Figure P7.2.7(b).
7.2.8A diode with thei–vcharacteristic shown in Figure
P7.2.8 is used in series with a voltage source of 5
V (forward bias) and a load resistance of 1 k.
(a) Determine the current and the voltage in the
load resistance.
(b) Find the power dissipated by the diode.
(c) Compute the load current for different load
resistance values of 2, 5, 0.5, and 0.2 k.*7.2.9The diode of Problem 7.2.8 is connected in series
with a forward-bias voltage of 10 V and a load
resistance of 2 k.
(a) Determine the load voltage and current.
(b) Calculate the power dissipated by the diode.
(c) Find the load current for different values of
supply voltage of 2.5, 5.0, 15.0, and 20.0 V.
7.2.10Consider a reverse-biased diode with a source
voltageVBin series with a load resistanceRL.
Write the KVL equation for the circuit.
7.2.11Two identical junction diodes whose volt–ampere
relation is given by Equation (7.2.1) in which
IS = 0. 1 μA,VT =25 mV, andη=2, are
connected as shown in Figure P7.2.11. Determine
the current in the circuit and the voltage across
each diode.
7.2.12Consider the diode of Problem 7.2.6 withVon=
0 .7 V and the model of Figure 7.2.5(a). Evaluate
the effect ofVonon the answer.
*7.2.13Consider the model of Figure 7.2.5(a). In the cir-
cuit of Figure P7.2.13, the diode is given to have
Von= 0 .7 V. Findi 1 andi 2 in the circuit.
7.2.14For the circuit shown in Figure P7.2.14(a), deter-
mine the diode current and voltage and the power
delivered by the voltage source. The diode char-
acteristic is given in Figure P7.2.14(b).
7.2.15Let the diode of Problem 7.2.14, with its givenv–i
curve, be connected in a circuit with an operating
point ofVd= 0 .6 V andId=2 mA. If the diode is
to be represented by the model of Figure 7.2.5(b),
determineRfandVon.
7.2.16Consider the circuit shown in Figure P7.2.16. De-
termine the current in the diode by assuming:
(a) The diode is ideal.
(b) The diode is to be represented by the model
of Figure 7.2.5(a) withVon= 0 .6V,and6 Device characteristic
5
4
3
2
10241536I, mAV, VFigure P7.2.6