Fundametals of Analog Electronics_part II

8/7/2019 Fundametals of Analog Electronics_part II

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Module: Fundamentals of Analog Electronics Module Number: ENRE213

Electronic Devices and Circuit Theory, 9th ed., Boylestad and Nashelsky

Lecturer: Dr. Omar Daoud

German-Jordanian University

School of Applied Natural Sciences -

Energy 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.


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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.


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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.


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Fig. 4.4 Baseemitter loop.Fig. 4.5 Collectoremitter 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.


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Emitter Bias

Fig. 4.17 BJT bias circuit with emitter resistor.Fig. 4.18 Baseemitter loop.

Fig. 4.19 Network derived from the result of Fig.4.18

Fig. 4.20 Reflected impedance level of RE.

Fig. 4.21 Collectoremitter loop.


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Design Operation

Transistor Switching Network

Fig. 4.48 Example 4.19. Fig. 4.49 Example 4.20.

Fig. 4.53 Transistor inverter.

Saturation conditions and the

resulting terminal resistance.

Cutoff conditions and the

resulting terminal resistance.


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Fig. 4.56 Inverter for Example 4.24.

Fig. 4.57 Defining the time intervals of a pulse waveform.


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School of Applied Natural Sciences -Energy Engineering

Bipolar Junction Transistor

AC Analysis: A model is an equivalent circuit that represents the AC characteristics of the

transistor.

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 reTransistor 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.


Fig. 5.6 (a) Common-base BJT transistor; (b) re model for the configuration of (a).

Fi . 5.7 Common-base re e uivalent circuit.

Fig. 5.9 Defining Av = Vo/Vi for the common-base configuration.


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Common Emitter Configuration

Common Collector Configuration

Use the common-emitter model for the common-collector configuration.

Fig. 5.11 (a) Common-emitter BJT transistor; (b) approximate model for the configuration of a).

Fig. 5.17 re model for the common-emitter transistorconfiguration.

Fig. 5.12 Determinin Zi usin the a roximate

Fig. 5.16 Determining the voltage and current gain for the

common-emitter transistor am lifier.


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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:

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

Fig. 5.24 Common-base configuration: (a) graphical symbol; (b) hybrid equivalent

circuit.


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Common-Emitter re vs. h-Parameter Model

Fig. 5.25 Effect of removing hre and hoe from the hybird equivalent circuit.

Fig. 5.26 Approximate hybrid equivalent model.

Fig. 5.27 Hybrid versus re model: (a) common-emitter configuration; (b) common-base configuration.


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School of Applied Natural Sciences -

Energy Engineering

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. 5.35Network of Fig. 5.34 following the removalof the effects ofVCC, C1 and C2.

Fig. 5.36 Substituting the re model into the network of Fig.5.35.

Fig. 5.37DeterminingZo for the network of Fig. 5.36.

Co 10Rr

e

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


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Common Emitter Voltage-divider Bias

Fig. 5.39 Example 5.4.

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,10Rr

i

oi

10Rr

ei

oi

eCo

o

i

oi

I

IA

rR

R

I

IA

)rR)(R(rrR

IIA

C

ivi

R

ZAA

Co 10Rr

e

C

i

ov

e

oC

i

ov

r

R

V

VA

r

r||R

V

VA

Fig. 5.38 Demonstrating the 180 phase shift between input and outputwaveforms.


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Common Emitter Bias

Fig. 5.43 CEemitter-bias configuration.Fig. 5.46 Example 5.6.


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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.

Fig. 5.44 Substituting the re equivalent circuit into the ac equivalent

network of Fig. 5.43.

Eb

Eeb

RZ

E

C

i

ov

)R(rZ

Ee

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

Fi . 5.46 Exam le 5.6.


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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

IAi

oi



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Fundametals of Analog Electronics_part II

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