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Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II 1
Philadelphia University Faculty of Engineering
Communication and Electronics Engineering
Bipolar Junction Transistor
Configurations:
Common Base Configuration
Fig. 3.2 Types of transistors: (a) pnp; (b) npn.
Fig. 3.6 Notation and symbols used with the common-base configuration: npn transistor.
Fig. 3.8 Output or collector characteristics for a common-base transistor amplifier.
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II 2
Common Emitter Configuration
Common Collector Configuration
Fig. 3.13 Notation and symbols used with the common-emitter configuration: npn transistor
Fig. 3.14 Characteristics of a silicon transistor in the common-emitter configuration: (a) collector characteristics; (b) base characteristics.
Fig. 3.20 Notation and symbols used with the common-collector configuration: (a) pnp transistor; (b) npn transistor.
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II 3
Operating Point
Fixed Bias Circuit
Fig. 4.1 Various operating points within the limits of operation of a transistor.
Fig. 4.2 Fixed-bias circuit.
Fig. 4.3 DC equivalent of Fig. 4.2.
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II 4
Fig. 4.4 Base–emitter loop.
Fig. 4.5 Collector–emitter loop.
Fig. 4.7 DC fixed-bias circuit for Example 4.1.
Fig. 4.9 Determining ICsat. Fig. 4.10 Determining ICsat for the fixed-bias configuration.
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II 5
Example 4.1.:
Example 4.3:
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II 6
Emitter Bias
Fig. 4.17 BJT bias circuit with emitter resistor.
Fig. 4.18 Base–emitter loop.
Fig. 4.19 Network derived from the result of Fig. 4.18
Fig. 4.20 Reflected impedance level of RE.
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II 7
Fig. 4.21 Collector–emitter loop.
Fig. 4.14 Effect of an increasing level of RC on the load line
and the Q-point.
Fig. 4.15 Effect of lower values of VCC on the load line and the Q-point.
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II 8
Example 4.4:
Fig. 4.22 Emitter-stabilized bias circuit for Example 4.4.
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II 9
Example 4.7:
Fig. 4.31 Beta-stabilized circuit for Example 4.7.
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
10
Example 4.15:
Fig. 4.40 Collector feedback with RE = 0Ω
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
11
Example 4.16: Determine VC and VB for the network of Fig. 4.41.
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
12
Example 4.17:
Fig. 4.42 Common-base configuration.
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
13
Design Operation
Example 4.19:
Fig. 4.47 Example 4.19.
Fig. 4.48 Example 4.20.
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
14
Example 4.20:
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
15
Transistor Switching Network
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
16
Example 4.24:
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
17
AC Analysis: • A model is an equivalent circuit that represents the AC characteristics of the
transistor.
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
18
• A model uses circuit elements that approximate the behavior of the transistor. • There are two models commonly used in small signal AC analysis of a
transistor: – re model – Hybrid equivalent model
The re Transistor Model:
BJTs are basically current-controlled devices, therefore the re model uses a diode and a current source to duplicate the behavior of the transistor. One disadvantage to this model is its sensitivity to the DC level. This model is designed for specific circuit conditions.
Common Base Configuration
Common Emitter Configuration
Fig. 5.6 (a) Common-base BJT transistor; (b) re model for the configuration of (a).
Fig. 5.7 Common-base re equivalent circuit.
Fig. 5.9 Defining Av = Vo/Vi for the common-base configuration.
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
19
Common Collector Configuration Use the common-emitter model for the common-collector configuration.
The Hybrid Equivalent Model: The following hybrid parameters are developed and used for modeling the transistor. These parameters can be found in a specification sheet for a transistor:
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
20
• hi = input resistance • hr = reverse transfer voltage ratio (Vi/Vo) 0 • hf = forward transfer current ratio (Io/Ii) • ho = output conductance
Fig. 5.22 Complete hybrid equivalent circuit.
Fig. 5.23 Common-emitter configuration: (a) graphical symbol; (b) hybrid equivalent circuit
Fig. 5.24 Common-base configuration: (a) graphical symbol; (b) hybrid equivalent circuit.
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
21
Common-Emitter re vs. h-Parameter Model
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
22
BJT Amplifier Circuits:
Common Emitter Configurations:
Common Emitter Fixed-bias • The input is applied to the base • The output is from the collector • High input impedance • Low output impedance • High voltage and current gain • Phase shift between input and output is 180
Fig. 5.34 Common-emitter fixed-bias configuration.
Fig. 5.35 Network of Fig. 5.34 following the removal of the effects of VCC, C1 and C2.
Fig. 5.36 Substituting the re model into the network of Fig. 5.35.
Fig. 5.37Determining Zo for the network of Fig. 5.36.
Co 10Rre
Cv
e
oC
i
ov
r
RA
r
)r||(R
V
VA
eBCo r10R ,10Rri
eBCo
oB
i
oi
A
)r)(RR(r
rR
I
IA
C
ivi R
ZAA
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
23
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
24
Example 5.4:
Solution:
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
25
Common Emitter Voltage-divider Bias
Fig. 5.40 Voltage-divider bias configuration.
Fig. 5.41Substituting the re equivalent circuit into the ac equivalent network of Fig. 5.40.
eCo
Co
r10R ,10Rri
oi
10Rrei
oi
eCo
o
i
oi
I
IA
rR
R
I
IA
)rR)(R(r
rR
I
IA
C
ivi R
ZAA
Co 10Rre
C
i
ov
e
oC
i
ov
r
R
V
VA
r
r||R
V
VA
Fig. 5.42 Example 5.5.
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
26
Example 5.5:
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
27
Solution:
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
28
Common Emitter Bias 1) Unbypassed :
Fig. 5.43 CE emitter-bias configuration.
Fig. 5.44 Substituting the re equivalent circuit into the ac equivalent network of Fig. 5.43.
Fig. 5.46 Example 5.6.
Eb
Eeb
RZE
C
i
ov
)R(rZEe
C
i
ov
b
C
i
ov
R
R
V
VA
Rr
R
V
VA
Z
R
V
VA
bB
B
i
oi ZR
R
I
IA
C
ivi R
ZAA
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
29
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
30
Example 5.6:
Solution:
Common Base Configuration • The input is applied to the emitter. • The output is taken from the collector. • Low input impedance. • High output impedance. • Current gain less than unity. • Very high voltage gain. • No phase shift between input and output.
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
31
Fig. 5.57 Common-base configuration.
Fig. 5.58 Substituting the re equivalent circuit into the ac equivalent network of Fig. 5.57.
e
C
e
C
i
ov r
R
r
R
V
VA
1I
IA
i
oi
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
32
Example 5.11:
Solution:
Common Collector (Emitter follower) Configuration • The input is applied to the base. • The output is taken from the emitter. • The output voltage is slightly less than the input one (VoVi) • It is use for impedance-matching purposes • High input impedance. • Low output impedance. • No phase shift between input and output.
Fig. 5.59 Example 5.11.
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
33
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
34
Example 5.10:
Solution:
Fig. 5.54 Example 5.10.
Module: Electronics I Module Number: 610/650221-222 Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky
Lecturer: Dr. Omar Daoud Part II
35