Chapter 8 Bjt Small-Signal Analysis Essay

Presentation on theme: "Chapter 8: BJT Small-Signal Analysis"— Presentation transcript:

1 Chapter 8: BJT Small-Signal Analysis
Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

2 BJT Small Signal Analysis
Slide 1The re and hybrid models will be used to analyze AC small-signal transistor circuits.Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

3 Common-Emitter (CE) Fixed-Bias Configuration
Slide 2The input (Vi) is applied to the base and the output (Vo) is from the collector.The Common-Emitter is characterized as having high input impedance and low output impedance with a high voltage and current gain.Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

4 Removing DC effects of VCC and Capacitors
Slide 3Removing DC effects of VCC and CapacitorsRobert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

5 re Model Slide 4 Determine , re, and ro:
 and ro: look in the specification sheet for the transistor or test the transistor usinga curve tracer.re: calculate re using dc analysis:Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

6 Impedance Calculations
Slide 5Input Impedance:[Formula 8.1][Formula 8.2]Output Impedance:[Formula 8.3][Formula 8.4]Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

7 Gain Calculations Slide 6 Voltage Gain (Av): [Formula 8.5]
Current Gain (Ai):[Formula 8.7][Formula 8.8]Current Gain from Voltage Gain:[Formula 8.9]Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

8 Phase Relationship Slide 7
The phase relationship between input and output is 180 degrees. The negative sign used in the voltage gain formulas indicates the inversion.Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

9 CE – Voltage-Divider Bias Configuration
Slide 8CE – Voltage-Divider Bias ConfigurationRobert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

10 re Model Slide 9 You still need to determine , re, and ro.
Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

11 Impedance Calculations
Slide 10Input Impedance:[Formula 8.10][Formula 8.11]Output Impedance:[Formula 8.12][Formula 8.13]Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

12 Gain Calculations Slide 11 Voltage Gain (Av): [Formula 8.14]
Current Gain (Ai):[Formula 8.16][Formula 8.17][Formula 8.18]Current Gain from Voltage Gain:[Formula 8.19]Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

13 Phase Relationship Slide 12
A CE amplifier configuration will always have a phase relationship between input and output is 180 degrees. This is independent of the DC bias.Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

14 CE Emitter-Bias Configuration
Slide 13Unbypassed RERobert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

15 re Model Slide 14 Again you need to determine , re.
Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

16 Impedance Calculations
Slide 15Input Impedance:[Formula 8.20][Formula 8.21][Formula 8.22][Formula 8.23]Output Impedance:[Formula 8.33]Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

17 Gain Calculations Slide 16 Voltage Gain (Av): [Formula 8.25]
or [Formula 8.27]Current Gain (Ai):[Formula 8.28]Current Gain from Voltage Gain:[Formula 8.29]Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

18 Phase Relationship Slide 17
A CE amplifier configuration will always have a phase relationship between input and output is 180 degrees. This is independent of the DC bias.Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

19 CE Emitter-Bias Configuration
Slide 18Bypassed REThis is the same circuit as the CE fixed-bias configuration and therefore can be solved using the same re model.Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

20 Emitter-Follower Configuration
Slide 19You may recognize this as the Common-Collector configuration. Indeed they are the same circuit.Note the input is on the base and the output is from the emitter.Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

21 re Model Slide 20 You still need to determine , re, and ro.
Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

22 Impedance Calculations
Slide 21Input Impedance:[Formula 8.37][Formula 8.38][Formula 8.39][Formula 8.40]Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

23 Impedance Calculations (cont’d)
Slide 22Output Impedance:[Formula 8.42][Formula 8.43]Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

24 Gain Calculations Slide 23 Voltage Gain (Av): [Formula 8.44]
Current Gain (Ai):[Formula 8.46]Current Gain from Voltage Gain:[Formula 8.47]Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

25 Phase Relationship Slide 24
A CC amplifier or Emitter Follower configuration has no phase shift between input and output.Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

26 Common-Base (CB) Configuration
Slide 25The input (Vi) is applied to the emitter and the output (Vo) is from the collector.The Common-Base is characterized as having low input impedance and high output impedance with a current gain less than 1 and a very high voltage gain.Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

27 re Model Slide 26 You will need to determine  and re.
Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

28 Impedance Calculations
Slide 27Input Impedance:[Formula 8.54]Output Impedance:[Formula 8.55]Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

29 Gain Calculations Slide 28 Voltage Gain (Av): [Formula 8.56]
Current Gain (Ai):[Formula 8.57]Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

30 Phase Relationship Slide 29
A CB amplifier configuration has no phase shift between input and output.Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

31 CE Collector Feedback Configuration
Slide 30This is a variation of the CE Fixed-Bias configuration.Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

32 re Model Slide 31 You will need to determine  and re.
Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

33 Impedance Calculations
Slide 32Input Impedance:[Formula 8.58]Output Impedance:[Formula 8.59]Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

34 Gain Calculations Slide 33 Voltage Gain (Av): [Formula 8.60]
Current Gain (Ai):[Formula 8.61][Formula 8.62]Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

35 Phase Relationship Slide 34
This is a CE amplifier configuration; therefore there is a 180-degree phase shift between input and output.Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

36 Approximate Hybrid Equivalent Circuit
Slide 35The h-parameters can be derived from the re model:hie = re hib = rehfe =  hfb = -hoe = 1/roThe h-parameters are also found in the specification sheet for the transistor.Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

37 CE Fixed-Bias Configuration
Slide 36CE Fixed-Bias ConfigurationRobert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

38 Hybrid Equivalent Circuit
Slide 37Impedances: [Formula 8.83][Formula 8.84]Gain: [Formula 8.85][Formula 8.86]Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

39 CE Voltage-Divider Configuration
Slide 38CE Voltage-Divider ConfigurationRobert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

40 Hybrid Equivalent Circuit
Slide 39Impedances: [Formula 8.87][Formula 8.88]Gain: [Formula 8.89][Formula 8.90]Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

41 CE Unbypassed Emitter-Bias Configuration
Slide 40CE Unbypassed Emitter-Bias ConfigurationRobert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

42 Hybrid Equivalent Circuit
Slide 41Impedances: [Formula 8.91][Formula 8.92][Formula 8.93]Gain: [Formula 8.94][Formula 8.95][Formula 8.96]Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

43 CC or Emitter-Follower Configuration
Slide 42CC or Emitter-Follower ConfigurationRobert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

44 Hybrid Equivalent Circuit
Slide 43Impedances: [Formula 8.97][Formula 8.98][Formula 8.99]Gain: [Formula 8.100][Formula 8.101][Formula 8.102]Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

45 CB Configuration Slide 44 Robert Boylestad Digital Electronics
Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

46 Hybrid Equivalent Circuit
Slide 45Impedances: [Formula 8.103][Formula 8.104]Gain: [Formula 8.105][Formula 8.106]Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

47 Summary Table Slide 46a Robert Boylestad Digital Electronics
Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

48 Summary Table Slide 46b Robert Boylestad Digital Electronics
Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

49 Troubleshooting Slide 47
1. Check the DC bias voltages – if not correct check power supply, resistors, transistor. Also check to ensure that the coupling capacitor between amplifier stages is OK.2. Check the AC voltages – if not correct check transistor, capacitors and the loading effect of the next stage.Robert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

50 Practical Applications
Slide 48• Audio Mixer• Preamplifier• Random-Noise Generator• Sound Modulated Light SourceRobert Boylestad Digital ElectronicsCopyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

Пытаясь подняться на ноги, Стратмор в ужасе смотрел на предмет, зажатый в его пальцах: это была рука Чатрукьяна, обломившаяся в локтевом суставе. Наверху Сьюзан ждала возвращения коммандера, сидя на диване в Третьем узле словно парализованная. Она не могла понять, что задержало его так надолго. У ее ног лежало тело Хейла. Прошло еще несколько минут.

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