05 chapter bjt

Microelectronics Circuit Analysis and DesignCircuit Analysis and Design

Donald A. Neamen

Chapter 5Chapter 5

The Bipolar Junction Transistor

Neamen Microelectronics, 4e Chapter 5-1McGraw-Hill

In this chapter, we will:p ,

Discuss the physical structure and operation of the bipolar junction transistorthe bipolar junction transistor.

Understand the dc analysis and design techniques of bipolar transistor circuitstechniques of bipolar transistor circuits.

Examine three basic applications of bipolar t i t i ittransistor circuits.

Investigate various dc biasing schemes of bipolar t i t i it i l di i t t d i it transistor circuits, including integrated circuit biasing.C d h d b f l l Consider the dc biasing of multistage or multi-transistor circuits.


Cross Section of Integrated Circuit gnpn Transistor


Modes of OperationModes of Operation

Forward-Active Forward ActiveB-E junction is forward biasedB-C junction is reverse biasedB C junction is reverse biased

SaturationB-E and B-C junctions are forward biasedB E and B C junctions are forward biased

Cut-OffB-E and B-C junctions are reverse biased B E and B C junctions are reverse biased

Inverse-Active (or Reverse-Active)B-E junction is reverse biasedB-E junction is reverse biasedB-C junction is forward biased


npn BJT in Forward-Activenpn BJT in Forward Active


Electrons and Holes in npn BJTElectrons and Holes in npn BJT


Electrons and Holes in pnp BJTElectrons and Holes in pnp BJT


Circuit Symbols and Circuit Symbols and Current Conventions


Current RelationshipsCurrent Relationships

BCE iii

)1(

BC

iiii

)1(

EC

BE

iiii

EC

1


Common-Emitter ConfigurationsCommon Emitter Configurations


Common-Base ConfigurationCommon Base Configuration


Current-Voltage Characteristics of a Current Voltage Characteristics of a Common-Base Circuit


Current-Voltage Characteristics of a Current Voltage Characteristics of a Common-Emitter Circuit


Early Voltage/Finite Output Early Voltage/Finite Output Resistance


Effects of Leakage Currents Effects of Leakage Currents on I-V Characteristics


Effect of Collector-Base Breakdown Effect of Collector Base Breakdown on Common Base I-V Characteristics


Effect of Collector-Base Breakdown on Effect of Collector Base Breakdown on Common Emitter I-V Characteristics


DC Equivalent Circuit for DC Equivalent Circuit for npn Common Emitter


DC Equivalent Circuit for DC Equivalent Circuit for pnp Common Emitter


Load LineLoad Line


P bl S l i T h iProblem-Solving Technique:Bipolar DC Analysis

1. Assume that the transistor is biased in forward active modeforward active modea. VBE = VBE(on), IB > 0, & IC = IB

2. Analyze ‘linear’ circuit.a y e ea c cu t3. Evaluate the resulting state of transistor.

a. If VCE > VCE(sat), assumption is correctCE CE( ), pb. If IB < 0, transistor likely in cutoffc. If VCE < 0, transistor likely in saturation

4. If initial assumption is incorrect, make new assumption and return to Step 2.


Voltage Transfer Characteristic for Voltage Transfer Characteristic for npn Circuit


Voltage Transfer Characteristic for Voltage Transfer Characteristic for pnp Circuit


Digital LogicDigital Logic

Inverter NOR gate


Bipolar Inverter as AmplifierBipolar Inverter as Amplifier


Effect of Improper Biasing on Effect of Improper Biasing on Amplified Signal Waveform


Single Base Resistor BiasingSingle Base Resistor Biasing


Common Emitter with Voltage Common Emitter with Voltage Divider Biasing and Emitter Resistor

CCTH VRRRV )/([ 212


I t t d Integrated Circuit Bi iBiasing

21

1III QC

21


Multistage Cascade Transistor CircuitMultistage Cascade Transistor Circuit


Multistage Cascode Multistage Cascode Transistor Circuit


05 chapter bjt

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