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2.0 Diode Applications
2.1 Introduction
2.2 Load-Line Analysis
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2.0 Diode Applications
Drawing the load line and finding the point of operation.
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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.
VD
VR
2.0 Diode Applications
Example 2.1
VD = 0.7
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2.3 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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2.5 Parallel and Series-Parallel Configuations
Two diodes sharing the load current.
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Network for Example 2.15.
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2.6 AND/OR Gates
OR gate
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AND Gate
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2.7 Sinusoidal Inputs: Half-Wave Rectification
Conduction region (0→T/2).
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Average 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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2.8 Full-Wave Recification
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Conduction 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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Center-tapped transformer full-wave rectifier.
Network conditions for the positive region of vi.
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Network conditions for the negative region of vi.
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Bridge network for Example 2.19.
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Network of Fig. 2-65 for the positive region of vi.
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Redrawn network of Fig. 2-66.
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2.9 Clipper
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Series clipper with a dc supply.
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Example 2.20
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Response to a parallel clipper.
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Example 2.22.
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2.9 Clamp
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Applied signal and network for Example 2.24.
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2.11 Zener Diode
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Example 2.26
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The output voltage across the Zener is Vz.
The minimum value of RLmin is given by the equation,
Vz
RLmin
Vi.
R RLmin
RLmin
Vz.
R
Vi 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 IRLmin
IRLmin
Izm
IR
RLmax
RLmax
Vz
RLmax
Vz
RLmax
Vz
IR Izm
Vz
Vi Vz
R
Izm
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2.12 Voltage-Multiplier Circuits
Voltage Doubler
Half-wave doubler
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Voltage Tripler
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2.13Practical Applications
Inductor bypass with diode
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Protection using diodes
Battery backup
Polarity detector
Voltage reference levels
AC regulator & square-wave generator
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