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LAB 4 BIPOLAR JUNCTION TRANSISTORS (BJT)
DC BIASING
LEARNING OBJECTIVESBy the end of this experiment, you should be
able to:
Describe some of the properties of bipolar junction transistors.
Analysis and design basic transistors amplifier configurations.
MATERIALS
Transistors: 2N3904 NPN
Resistors: 1 x 240k, 1 x 2.2k, 1 x 430k, 1 x 2k, 1 x 1k, 1 x
39k,
1 x 10k, 1 x 3.9k, 1 x 1.5k.
Capacitors: 2 1F
EQUIPMENT
Tektronix PS280 DC Power Supply Fluke 45 Dual Display Multimeter
Tektronix CFG 253 3MHz Function Generator Hewlett Packard
Oscilloscope 100MHz 54600B
PRE-LAB ASSIGNMENT
Derive the equations for VC, VB, VE, VBE, VCE, IC, IB, and IE
for the circuits shown inFigures 4-1 through 4-3.
Figure 4-1 Figure 4-2 Figure 4-3
VC E.g.: VCC - ICRC
VB
VE
VBE
VCE
IC
IB
IE
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IN-LAB ACTIVITIES
1. Build the Fixed Biascircuit shown in Figure 4-1 on your
protoboard.
Figure 4-1: Fixed Bias Circuit
2. By using the DMM, measure each of the transistor node dc
voltages (VC, VB, VE,VBE, and VCE), and determine/calculate all of
the currents (IC, IB, and IE). Calculate
, and then calculate . Show your results to the instructor
before proceeding.
3. Repeat steps 1 and 2 for the Emitter Stabilized Bias circuit
shown in Figure 4-2.
Figure 4-2: Emitter Stabilized Bias Circuit
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4. Repeat steps 1 and 2 for the Voltage Divider circuit shown in
Figure 4-3.
Figure 4-3: Voltage Divider Bias Circuit
5. Record all your results in Table 4-1.
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Lab 4
RESULTS
measured calcula
Circuit VC (V) VB (V) VE (V) VBE (V) VCE (V) IC (mA) IB ( A) IE
(mA
Fixed
Bias
Emitter
Stabilized
Bias
Voltage
Divider
Bias
Table 4-1
Fixed Bias Circuit
RB: k
RC: k
Emitter Stabilized Bias Circuit
RB: k
RC: k
RE: k
Voltage Divi
RB1:
RB2:
RC:
RE:
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Lab 4 5
LAB 4 REPORT
1. By using only the and VBE obtained and the derived equations
(pre-lab assignment)calculate VC, VB, VE, VCE, IC, IB, and IE and
compare with in-lab activity results.
Calculate the percentage relative error between your measured
values and your calculated
(pre-lab assignment) values. Please show the workings
clearly.
Fixed Bias Circuit:
Measured Calculated %error
VCVBVEVCEICIBIE
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Lab 4 6
Emitter Stabilized Bias Circuit:
Measured Calculated %errorVCVBVEVCEICIBIE
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Lab 4 7
Voltage Divider Bias Circuit:
Measured Calculated %error
VCVBVEVCEICIBIE
