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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 20 of 31Example 2.20
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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 26 of 31Example 2.26
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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