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Assignment 2
(Due: 9 July 2012)
1.
Given: Is = 1uA, n = 1 and VT = 26mV. If the diode current, ID = 50mA, calculate VD.
2.
For the circuits shown in Figure 1, determine I and V. [Assume: (a) ideal diode; (b) Ge;
(c) Si; (d) GaAs].
Figure 1
3.
For the circuits shown in Figure 2, determine V1 and V2.
+V1
1.2 k
Si
Si
10 V
+V2
+V1
4.7 k
12 V
+V2
4.7 k
Ge
 2V
 2V
(a)
(b)
Figure 2
4.
Sketch the output waveform, vO, for the circuits shown in Figure 3. Assume silicon
diode. Given: input voltage, vI = 10 Vpeak , frequency, f = 1 kHz.
Figure 3
5.
Refer to the rectifier circuit in Figure 4. Assuming ideal diodes,
a) Sketch and label the output voltage waveform.
b) Calculate the average value of the output voltage, vO and the load current, iO.
c) Determine the peak inverse voltage of the diodes.
d) If D1 is open circuited, sketch and label the output voltage waveform.
e) If D4 is open circuited, sketch and label the output voltage waveform.
f) If the positions of all diodes are reversed, sketch and label the output waveform.
D4
D1
D2
D3
iO
vi
240V
50Hz
100 
+
vO
_
20 : 1
Figure 4
6.
Referring to Figure 5, sketch and label the output waveform, vo. Determine the average
output voltage, VDC.
3:1
+
Si
 vo +
2 k
240 Vpeak
0.5 k
Si

2 k
Figure 5
7.
Referring to Figure 6;
a) Sketch and label the output waveform.
b) Determine the average output voltage.
c) Determine the peak inverse voltage of the diodes.
1:1
GaAs
+
D1
+ vo
120 Vrms
D2

2.4 k
GaAs
Figure 6