Microelectronics Circuit Analysis and Design

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Microelectronics Circuit Analysis and Design

• Donald A. Neamen
• Chapter 5
• The Bipolar Junction Transistor

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In this chapter, we will

• Discuss the physical structure and operation of
  the bipolar junction transistor.
• Understand the dc analysis and design techniques
  of bipolar transistor circuits.
• Examine three basic applications of bipolar
  transistor circuits.
• Investigate various dc biasing schemes of bipolar
  transistor circuits, including integrated circuit
  biasing.
• Consider the dc biasing of multistage or
  multi-transistor circuits.

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Cross Section of Integrated Circuit npn
Transistor
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Modes of Operation

• Forward-Active
• B-E junction is forward biased
• B-C junction is reverse biased
• Saturation
• B-E and B-C junctions are forward biased
• Cut-Off
• B-E and B-C junctions are reverse biased
• Inverse-Active (or Reverse-Active)
• B-E junction is reverse biased
• B-C junction is forward biased

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npn BJT in Forward-Active
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Electrons and Holes in npn BJT
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Electrons and Holes in pnp BJT
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Circuit Symbols and Current Conventions
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Current Relationships
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Common-Emitter Configurations
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Common-Base Configuration
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Current-Voltage Characteristics of a Common-Base
Circuit
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Current-Voltage Characteristics of a
Common-Emitter Circuit
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Early Voltage/Finite Output Resistance
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Effects of Leakage Currents on I-V
Characteristics
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Effect of Collector-Base Breakdown on Common Base
I-V Characteristics
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Effect of Collector-Base Breakdown on Common
Emitter I-V Characteristics
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DC Equivalent Circuit for npn Common Emitter
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DC Equivalent Circuit for pnp Common Emitter
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Load Line
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Problem-Solving TechniqueBipolar DC Analysis

• Assume that the transistor is biased in forward
  active mode
• VBE VBE(on), IB gt 0, IC bIB
• Analyze linear circuit.
• Evaluate the resulting state of transistor.
• If VCE gt VCE(sat), assumption is correct
• If IB lt 0, transistor likely in cutoff
• If VCE lt 0, transistor likely in saturation
• If initial assumption is incorrect, make new
  assumption and return to Step 2.

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Voltage Transfer Characteristic for npn Circuit
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Voltage Transfer Characteristic for pnp Circuit
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Digital Logic
Inverter
NOR gate
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Bipolar Inverter as Amplifier
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Effect of Improper Biasing on Amplified Signal
Waveform
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Single Base Resistor Biasing
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Common Emitter with Voltage Divider Biasing and
Emitter Resistor
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Integrated Circuit Biasing
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Multistage Cascade Transistor Circuit
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Multistage Cascode Transistor Circuit