ECE 250 Homework #7
Due 5/4/04
Problem 1:
+
R1
2000
0
+
-
V1
DC = 6
+
R2
2000
0
Vd
+
R3
1000
-
+
Transient
Analysis
V2
AMPLITUDE = 0.3
FREQUENCY = 1k
D8
D1N4148
0
a) Calculate the diode DC current and voltage.
b) Calculate the diode small signal resistance.
c) Calculate the diode ac voltage and current.
d) Use a Transient analysis with PSpice to find the diode ac voltage and current.
e) Compare your PSpice and hand calculations.
(To solve this problem properly, you will need to find the PSpice model for the D1N4148 and locate the values for the
saturation current and emission coefficient used by PSpice.)
Problem 2: Book Problem 1.36 on page 46.
Problem 3:
A new diode has been discovered that has the following current-voltage characteristics:
⎩
⎨
⎧≥
=otherwise
VforV
IDD
D0
0
2/5
ρ
where 2/5
50V
A
µ
ρ
=
Note that the current direction and voltage reference for ID and VD are the same for a standard semiconductor diode.
+
R
1k
0
+
-
Vin
DC = 12
VoVin
D1
a) For the circuit above, find numerical values of ID and VD. (VD will not be 0.7 volts.)
b) Find an equation for the small signal resistance of this diode, rd.
c) What is the value of this resistance at the operating point found in part a?
Problem 4):
An ancient semiconductor fossil was recently unearthed by paleontologists called transistosaur. After extracting the DNA
from this fossil, scientists were able to recreate a working device. It will soon be available in mass quantities from
semiconductor manufacturers.
