Week 3 Lab Instructions
Bipolar
Junction Transistor Amplifier Circuit Analysis
I. Objectives:
·
To analyze bipolar junction transistor (BJT)
common emitter (CE) amplifiers using the amplifier parameters.
·
To determine the BJT voltagedivider
biased DC parameters based on schematic diagrams, simulated circuits, and
constructed circuits.
·
To verify the operations of CE
amplifier based on the theatrical framework (laws and theorems).
·
To determine the phase angle between input
and output signals.
II. Equipment and Parts
List
Equipment:
·
Personal computer (PC) or compatible
·
Function generator
·
DMM (digital multimeter)
·
Variable DC power supply
·
Oscilloscope
Parts:
Qty.

Parts and Components

Tolerance Band

Wattage Rating, W



1

2N3904
Transistor




1

470 ? Resistor

gold

¼


1

2 K? Resistor

gold

¼


1

10 K? Resistor

gold

¼


1

47 K? Resistor

gold

¼


1

1.0 uF
Capacitor




1

10 uF
Capacitor




1

Proto
Board





Hookup
wires of different colors




3

BNC to
split ends cable




Software: MultiSim
III.
Procedure
A. Theoretical Analysis
Given
the schematic diagram shown in Figure 1, calculate the BJT voltagedivider biased
DC parameters (V_{B,} V_{C,} V_{E}, V_{CE,} V_{BE,
}V_{CEQ,}I_{B,}I_{c,}I_{E}, and I_{CQ})
with assumption h_{FE} = 50. Enter the calculated values in Table 1 on the
worksheet.
Note:
V_{B,} V_{C,} V_{E} are referred to point voltages, and
they are quantified with respect the circuit reference (i.e., ground); while, V_{CE,}
V_{BE,}are known as voltage drop across two points.
Figure 1 VoltageDivider
Biased Common Emitter (CE) Amplifier Schematic Diagram
Calculated Parameters

Voltage (V)

Current (mA)

Base
Voltage (V_{B})




Collector
Voltage (V_{C})




Emitter
Voltage (V_{E})




CollectorEmitter
Voltage (V_{CE})




BaseEmitter
Voltage (V_{BE})




CollectorEmitter
Voltage @ Cutoff (V_{CE(off)})




CollectorEmitter
Voltage (V_{CEQ})




Base
current (I_{B})




Collector
current (I_{c})




Emitter
current (I_{E})




Collector
current @ Saturation (I_{c(STA)})




Collector
current (I_{CQ})




Table 1
B.
MultiSim
Simulation
1. Design the circuit shown in Figure 2 using MultiSIM. Set the DC voltage
source to 9V for V_{CC}.
2. Measure the BJT voltagedivider biased DC parameters (V_{B,} V_{C,}
V_{E}, V_{CE,} V_{BE,}I_{B,}I_{c,}and
I_{E}).
3. Calculate (V_{CEQ} and I_{CQ}) based on the measured
values and h_{FE} = 50. Enter the measured and calculated values in
Table 2 on the worksheet.
Figure 2VoltageDivider
Biased Common Emitter (CE) AmplifierMultiSim Design
Simulated and
Calculated Parameters

Voltage (V)

Current (mA)

Base
Voltage (V_{B})




Collector
Voltage (V_{C})




Emitter
Voltage (V_{E})




CollectorEmitter
Voltage (V_{CE})




BaseEmitter
Voltage (V_{BE})




CollectorEmitter
Voltage @ Cutoff (V_{CE(off)})




CollectorEmitter
Voltage (V_{CEQ})




Base
current (I_{B})




Collector
current (I_{c})




Emitter
current (I_{E})




Collector
current @ Saturation (I_{c(STA)})




Collector
current (I_{CQ})




Table 2
4. Connect the input (V_{in}) and output (V_{out}) of the
amplifier to two separate channels of an oscilloscope.
5. Connect the input (V_{in}) of the amplifier to a function
generator and set the parameters of the functions generator to: (a) sinewave
mode at 1 kHz, and (b) amplitude of signal to 0.5 V peakto peak (V_{PP}).
If the output signal (V_{out}) is clipped, reduce the input signal amplitude
until the clipping no longer exists. A typical scope display is shown in Figure
3.
Figure
3 captured input and output signal waveforms of the simulated circuit on the oscilloscope
6. Capture the input and output signal waveforms and insert them on the
worksheet with proper caption. Then, answer the following questions on the
worksheet.
a. What is the V_{PP} of the input signal V_{in}?__________________V
b. What is the V_{PP} of the output signal V_{out}?________________V
c. What is the phase angle between the input and output signals?_________Degrees
d. Calculate the voltage gain (A_{V}) of this amplifier?
_________________
7. Reduce the amplitude of the input signal to onehalf the amount used in Step
3.
8. Capture the input and output signal waveforms and insert them on the
worksheet with proper caption. Then, answer the following questions on the
worksheet.
a. What is the V_{PP} of the input signal V_{in}?__________________V
b. What is the V_{PP} of the output signal V_{out}?________________V
c. What is the phase angle between the input and output signals?_________Degrees
d. Calculate the voltage gain (A_{V}) of this amplifier?
_________________
C.
Breadboard
Construction
1. Construct
the circuit in Figure 1 on a breadboard.
2. Set the DC
voltage source to 9V for VCC. Measure the
BJT voltagedivider biased DC parameters(V_{B,}
V_{C,} V_{E}, V_{CE,} V_{BE,}I_{B,}I_{c,
}and I_{E}). A typical collector (V_{C}) voltage
measurement is shown in figure 4.
3. Calculate(V_{CEQ}and I_{CQ}) based on the measured valuesandh_{FE} = 50.Enter the
measured and calculated values in Table 3 on the worksheet.
Figure 4VoltageDivider
Biased Common Emitter (CE) Amplifier constructed circuit
Measured and
calculated Parameters

Voltage (V)

Current (mA)

Base
Voltage (V_{B})




Collector
Voltage (V_{C})




Emitter
Voltage (V_{E})




CollectorEmitter
Voltage (V_{CE})




BaseEmitter
Voltage (V_{BE})




CollectorEmitter
Voltage @ Cutoff (V_{CE(off)})




CollectorEmitter
Voltage (V_{CEQ})




Base
current (I_{B})




Collector
current (I_{c})




Emitter
current (I_{E})




Collector
current @ Saturation (I_{c(STA)})




Collector
current (I_{CQ})




Table 3
4. Connect the input (V_{in}) and output (V_{out}) of the
amplifier to two separate channels of an oscilloscope.
5. Connect the input (V_{in}) of the amplifier to a function
generator and set the parameters of the functions generator to: (a) sinewave
mode at 1 kHz, and (b) amplitude of signal to 0.5 V peakto peak (V_{PP}).
If the output signal (V_{out}) is clipped, reduce the input signal
amplitude until the clipping no longer exists. A typical scope display is shown
in Figure 5.
Figure
5 captured input and output signal waveforms of the constructed circuit on the
oscilloscope.
6. Capture the input and output signal waveforms and insert them on the
worksheet with proper caption. Then, answer the following questions on the
worksheet.
a. What is the V_{PP} of the input signal V_{in}?__________________V
b. What is the V_{PP} of the output signal V_{out}?________________V
c. What is the phase angle between the input and output signals?_________Degrees
d. What is the voltage gain (A_{V}) of this amplifier?
_________________
7. Reduce the amplitude of the input signal to onehalf the amount used in Step
5.
8. Capture the input and output signal waveforms and insert them on the
worksheet with proper caption. Then, answer the following questions on the
worksheet.
a. What is the V_{PP} of the input signal V_{in}?__________________V
b. What is the V_{PP} of the output signal V_{out}?________________V
c. What is the phase angle between the input and output signals?_________Degrees
d. What is the voltage gain (A_{V}) of this amplifier?
_________________
IV. Results
Analysis
1.
Compare the calculated,simulated,
and measured parameter values, and enter your comments on the worksheet. Be
sure to calculate the percentage of error in each method and to identify the
source/s of error.
2.
Plot the DC loadline and
identify the Qpoint for the calculated,simulated, and measured
methods. Explain the significance of
shifting the Qpoint on the DC line and which method will result in better
Qpoint.
IV. Troubleshooting
Describe
any problems encountered and how those problems were solved.
V. Questions
Please provide the answer to the following questions
on the worksheet.
1. Did your theoretical calculations
closely match the results obtained from the MultiSim simulation? (Yes/ No).
Comments:
2. Did your theoretical
calculations closely match the results obtained from the constructed circuit?
(Yes/ No).
Comments:
3. Did your results
obtained from the Multisim simulation closely match the results obtained from
the constructed circuit? (Yes/ No).
Comments:
VI. Grading
Deliverable

% of Grade

Points
Achieved

Statistics (calculations, accurate values)

15


Diagrams (labels, accuracy)

6


Analysis (interpretation and discussion
results)

6


Organization (format of results and style)

3


Total
Points

30

