2_DiodeApplications

8/7/2019 2_DiodeApplications

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2.0 Diode Applications 1 of 312.1 Introduction

2.2 Load-Line Analysis


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2.0 Diode Applications 2 of 31Drawing the load line and finding the point of operation.

Drawing the load line.1) Redraw the circuit with the diode on the right.

2) Remove the diode and find a couple of points on the curve of VD vs. ID.

Convenient points are, the current when VD = 0 and the voltage when ID = 0.

Draw the line connecting these two points and note the voltage on the horizontal axis.

Note the intersection point.

VRVD


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2.0 Diode Applications 3 of 31Example 2.1

VD = 0.7


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2.0 Diode Applications 4 of 312.3 Diode Approximations

Series Diode Configurations with DC Inputs(a) Circuit; (b) characteristics

Silicon 0.7

Germanium 0.3

Series Diode Configurations.

Circuit for Example 2.11.


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2.0 Diode Applications 5 of 312.5 Parallel and Series-Parallel Configuations

Two diodes sharing the load current.


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2.0 Diode Applications 7 of 312.6 AND/OR Gates

OR gate


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2.0 Diode Applications 8 of 31AND Gate


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2.0 Diode Applications 9 of 312.7 Sinusoidal Inputs: Half-Wave Rectification

Conduction region (0T/2).


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2.0 Diode Applications 10 of 31Average voltage output

Vavg 0.318(Vm - VT )

Effect of VT on half-wave rectified signal.

Silicon diode, VT = 0.7

Vavg 0.318(Vm - VT )


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2.0 Diode Applications 11 of 312.8 Full-Wave Recification


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2.0 Diode Applications 12 of 31Conduction path for the positive region of vi.

Conduction path for the negative region of vi.

Input and output waveforms for a full-wave rectifier.

Vavg 0.636Vm Vavg 0.636(Vm - VT )


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2.0 Diode Applications 13 of 31Center-tapped transformer full-wave rectifier.

Network conditions for the positive region of vi.


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2.0 Diode Applications 14 of 31Network conditions for the negative region of vi.


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2.0 Diode Applications 15 of 31Bridge network for Example 2.19.


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2.0 Diode Applications 16 of 31Network of Fig. 2-65 for the positive region of vi.


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2.0 Diode Applications 17 of 31Redrawn network of Fig. 2-66.


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2.0 Diode Applications 18 of 312.9 Clipper


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2.0 Diode Applications 19 of 31Series clipper with a dc supply.


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2.0 Diode Applications 21 of 31Response to a parallel clipper.


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2.0 Diode Applications 22 of 31Example 2.22.


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2.0 Diode Applications 23 of 312.9 Clamp


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2.0 Diode Applications 24 of 31Applied signal and network for Example 2.24.


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2.0 Diode Applications 25 of 312.11 Zener Diode


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2.0 Diode Applications 27 of 31The output voltage across the Zener is Vz.

The minimum value of RLmin is given by the equation,

Vz ViRLmin

R RLmin.

R RLminVi

RLmin

RLmin

RLminR

VzVi Vz

.VzVi Vz

Now to find the maximum value of RL. As the value of RL is

increased the current through the Zener is increased.

Izm IR IRLminIR IRLmin

IRLmin

Vz

RLmax

Vz

RLmax

Izm IR Vz

RLmaxIR

Vz

RLmax

RLmaxVz

IR Izm

Vz

IR Izm

RLmaxVz

Vi Vz

RIzm

RIzm

Vz

Vi VzIzm

2 0 Di d A li i 28 f 31


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2.0 Diode Applications 28 of 312.12 Voltage-Multiplier Circuits

Voltage Doubler

Half-wave doubler

2 0 Di d A li ti 29 f 31


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2.0 Diode Applications 29 of 31Voltage Tripler


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2 0 Diode Applications 31 of 31


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2.0 Diode Applications 31 of 31Protection using diodes

Battery backup

Polarity detector

Voltage reference levelsAC regulator & square-wave generator

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2_DiodeApplications