Lab 4 BJT-DC Biasing 1 1112

8/11/2019 Lab 4 BJT-DC Biasing 1 1112

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COURSE CODE: EXPERIMENT NO: 4

COURSE INSTRUCTOR: DATE:

TITLE: MARKS

OBJECTIVE:

PRELAB :

1 / 1

2 / 1

3 / 2

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EXPERIMENT RESULT:

R measured / 2

Table 4-1 / 6

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POST LAB:

Fixed Bias / 2

Emmitter Stabilized Bias / 2

Voltage Divider Bias / 3

/ 7

CONCLUSION: / 1

INSTRUCTOR COMMENTS: TOTAL

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UNIVERSITI TENAGA NASIONAL

Dept of Electronics and Communication Engineering

College of Engineering

EEEB141

Bipolar Junction Transistor (BJT) - DC Biasing

The objectives of this laboratory experiment is to describe some properties of BJT and analyze and design

basic BJT amplifiers

Semester: 2 Academic Year: 2011 / 2012

TIME:

STUDENT NAME: STUDENT ID:

SECTION:

WORKBENCH NO:GROUP MEMBER: STUDENT ID:


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LAB 4 BIPOLAR JUNCTION TRANSISTORS (BJT)DCBIASING

LEARNING OBJECTIVESBy the end of this experiment, you should be able to:

Describe some of the properties of bipolar junction transistors.

Analyze 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

DC Power Supply

Dual Display Multimeter

Function Generator

BACKGROUND

The Bipolar Junction Transistor (BJT) has three separately doped regions and contains two

pn junctions. It can be modeled as a current controlled current source. The circuit symboland the pin out of the device can be seen in figure below.

In analyzing a BJT circuit the following simplified equations can be used:

IC IB

The equation assumes the device operating in active region (typical for amplifier

applications). The equation shows that the current through the collector of the device is

controlled by the current to the base. Hence, the current through the current changed

proportionally if the base current is changed.

B

C

E BE C

IB

IC

IE

+

-

VBE


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PRE-LAB ASSIGNMENTS

1. Write the Kirchoffs voltage law equation for the right (in terms of VCC, RC, , IB and

VCE) and left hand side (in term of VCC, RB, IBand VBE) of Figure 4-1.

2.

Write the Kirchoffs voltage law equation for the right (in terms of VCC, RC, , IB and

VCE) and left hand side (in term of VCC, RB, RE, IBand VBE) of Figure 4-2.

3. Write the appropriate Kirchoffs voltage (and/or current) law equation using VTH and

RTHfor Figure 4-3.


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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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EEEB 141 ELECTRONICS DESIGN LAB, Lab 4 5

RESULTS

measured calculated

Circuit VC(V) VB(V) VE(V) VBE(V) VCE(V) IC(mA) IB(A) IE(mA)C

B

I

I = C

E

I

I =

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 Divider Bias Circuit

RB1: k

RB2: k

RC: k

RE: k


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POST LAB DISCUSSIONS

1. By using only the and VBEobtained and the measured resistors value,calculate VC,VB, VE, and VCE and compare with in-lab activity results. Calculate the percentagerelative error between your measured values and your calculated values.Please show the

workings clearly.

Fixed Bias Circuit:

Measured Calculated %errorVCVBVEVCE


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Emitter Stabilized Bias Circuit:

Measured Calculated %errorVCVBVEVCE


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Voltage Divider Bias Circuit:

Measured Calculated %error

VCVBVEVCE


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CONCLUSIONS

Lab 4 BJT-DC Biasing 1 1112

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