BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 ·...
Transcript of BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 ·...
![Page 1: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/1.jpg)
Lecture #4 BJT Modeling and re Transistor Model (small signal analysis) Instructor: Dr. Ahmad El-Banna
Benha University Faculty of Engineering at Shoubra
Oc
to
ber
2014
ECE-312 Electronic Circuits (A)
© A
hmad
El-B
anna
![Page 2: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/2.jpg)
Remember ! Lectures List
2
ECE-
312
, Lec
#4 , O
ct 20
14
Week#1 • Lec#1: Introduction and Basic Concepts
Week#2
• Lec#2: BJT Review
• Lec#3: BJT Biasing Circuits
Week#3
• Lec#4: BJT Modeling and re Transistor Model
• Lec#5: Hybrid Equivalent Model
Week#4
• Lec#6: BJT Small-Signal Analysis
• Lec#7: Systems Approach
Week#5
• Lec#8: General Frequency Considerations
• Lec#9: BJT Low Frequency Response
Week#6
• Lec#10: BJT High Frequency Response
• Lec#11: Multistage Frequency Effects and Square-Wave Testing
© A
hmad
El-B
anna
![Page 3: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/3.jpg)
Remember ! Lectures List
3
ECE-
312
, Lec
#4 , O
ct 20
14
Week#1 • Lec#1: Introduction and Basic Concepts
Week#2
• Lec#2: BJT Review
• Lec#3: BJT Biasing Circuits
Week#3
• Lec#4: BJT Modeling and re Transistor Model
• Lec#5: Hybrid Equivalent Model
Week#4
• Lec#6: BJT Small-Signal Analysis
• Lec#7: Systems Approach
Week#5
• Lec#6: General Frequency Considerations
• Lec#7: BJT Low Frequency Response
Week#6
• Lec#8: BJT High Frequency Response
• Lec#9: Multistage Frequency Effects and Square-Wave Testing
© A
hmad
El-B
anna
Merged in two lectures only
![Page 4: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/4.jpg)
Agenda
Amplification in the AC Domain
BJT transistor Modeling
The re Transistor Model (small signal analysis)
Effect of RL and Rs (System approach)
Determining the Current Gain
Summary Table 4
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 5: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/5.jpg)
AMPLIFICATION IN THE AC DOMAIN 5
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 6: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/6.jpg)
Amplification in the AC Domain
6
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
• The superposition theorem is applicable for the analysis and design of the dc and ac components of a BJT network, permitting the separation of the analysis of the dc and ac responses of the system.
![Page 7: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/7.jpg)
BJT TRANSISTOR MODELING 7
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 8: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/8.jpg)
BJT Transistor Modeling
8
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
• A model is a combination of circuit elements, properly chosen, that best approximates the actual behavior of a semiconductor device under specific operating conditions.
Ac analysis
• Defining the important parameters of any system.
![Page 9: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/9.jpg)
BJT Transistor Modeling
9
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
• the ac equivalent of a transistor network is obtained by: 1. Setting all dc sources to zero and replacing them by a short-circuit equivalent 2. Replacing all capacitors by a short-circuit equivalent 3. Removing all elements bypassed by the short-circuit equivalents introduced by steps 1 and 2 4. Redrawing the network in a more convenient and logical form
![Page 10: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/10.jpg)
THE re TRANSISTOR MODEL
• Common Emitter Configuration
• Common Base Configuration
• Common Collector Configuration
• re Model in Different Bias Circuits
10
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 11: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/11.jpg)
The re Transistor Model (CE)
11
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 12: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/12.jpg)
The re Transistor Model (CB)
12
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 13: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/13.jpg)
The re Transistor Model (CC)
13
ECE-
312
, Lec
#4 , O
ct 20
14
• For the common-collector configuration, the model defined for the common-emitter configuration of is normally applied rather than defining a model for the common-collector configuration.
• The dc analysis of npn and pnp configurations is quite different in the sense that the currents will have opposite directions and the voltages opposite polarities.
• However, for an ac analysis where the signal will progress between positive and negative values, the ac equivalent circuit will be the same.
npn versus pnp
© A
hmad
El-B
anna
![Page 14: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/14.jpg)
C.E. Fixed Bias Configuration
14
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 15: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/15.jpg)
Voltage-Divider Bias
15
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 16: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/16.jpg)
C.E. Emitter Bias Configuration
16
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 17: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/17.jpg)
C.E. Emitter Bias Configuration..
17
ECE-
312
, Lec
#4 , O
ct 20
14
Same as CE fixed bias config.
© A
hmad
El-B
anna
![Page 18: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/18.jpg)
Emitter Follower Configuration
18
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 19: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/19.jpg)
Emitter Follower Configuration..
19
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 20: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/20.jpg)
Common-Base Configuration
20
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 21: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/21.jpg)
Collector-Feedback Configuration
21
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 22: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/22.jpg)
Collector-Feedback Configuration..
22
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 23: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/23.jpg)
Collector DC Feedback Configuration
23
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 24: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/24.jpg)
EFFECT OF RL AND RS
(SYSTEM APPROACH)
24
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 25: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/25.jpg)
Effect of RL and Rs
25
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
• The loaded voltage gain of an amplifier is always less than the no-load gain. • The gain obtained with a source resistance in place will always be less than that obtained under
loaded or unloaded conditions due to the drop in applied voltage across the source resistance. • For the same configuration AvNL>AvL> Avs. • For a particular design, the larger the level of R L , the greater is the level of ac gain. • For a particular amplifier, the smaller the internal resistance of the signal source, the greater is
the overall gain. • For any network that have coupling capacitors, the source and load resistance do not affect the dc
biasing levels.
![Page 26: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/26.jpg)
Effect of RL and Rs ..
26
ECE-
312
, Lec
#4 , O
ct 20
14
Voltage-divider ct.
Emitter- Follower Ct.
© A
hmad
El-B
anna
![Page 27: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/27.jpg)
DETERMINING THE CURRENT GAIN 27
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 28: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/28.jpg)
Determining the Current gain
28
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
• For each transistor configuration, the current gain can be determined directly from the voltage gain, the defined load, and the input impedance.
![Page 29: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/29.jpg)
SUMMARY TABLE 29
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 30: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/30.jpg)
30
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 31: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/31.jpg)
31
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 32: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/32.jpg)
32
ECE-
312
, Lec
#4 , O
ct 20
14
© A
hmad
El-B
anna
![Page 33: BJT Modeling and r Model (small signal analysis) e Transistor 2014 Shoubra... · 2014-10-27 · Transistor Model •Lec#5: Hybrid Equivalent Model Week#4 •Lec#6: BJT Small-Signal](https://reader034.fdocuments.us/reader034/viewer/2022043003/5f8160a932f7d73aad6fdd0a/html5/thumbnails/33.jpg)
• For more details, refer to:
• Chapter 5 at R. Boylestad, Electronic Devices and Circuit Theory, 11th edition, Prentice Hall.
• The lecture is available online at:
• http://bu.edu.eg/staff/ahmad.elbanna-courses/11966
• For inquires, send to:
33
ECE-
312
, Lec
#1 , O
ct 20
14
© A
hmad
El-B
anna