ANALOG ELECTRONIC (BEL 10203)

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ANALOGELECTRONIC (BEL 10203)

• By
• DR. NAFARIZAL BIN NAYAN
• Department of Electronic Engineering
• Faculty of Electrical and Electronic Engineering
• Universiti Tun Hussein Onn Malaysia

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2. DIODE CIRCUITS AND THEIR APPLICATIONS
Diode characteristic
Diode circuit analysis Diode applications Half-w
ave rectifier Full-wave rectifier Clipping
circuit Clamping circuit
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Diode characteristic
From Kirchoffs Voltage Law (KVL),
Plot this equation to ID-VD graph
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Diode characteristic and load line
If ID0, VDVss
If VD0, IDVss/R
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Diode approximation
() (-)
Forward biased
Reverse biased
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• Offset voltage for diode

Silicon
Ideal
id
id
vd
vd
0.7
0
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Diode circuit analysis
Tutorial Example 2.1-2.4
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Diode applications Half-wave rectifier Full-wav
e rectifier Clipping circuit Clamping circuit
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Half-wave rectifier
Forward biased
Reverse biased
Average value
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Full-wave rectifier
Positive half-cycle
Negative half-cycle
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Full-wave rectifier
One can also construct a full-wave rectifier
circuit using four diodes. ? Bridge rectifier
circuit
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Clipping circuit
Clippers are networks that employs diodes to
clip away a portion of an input signal without
distorting the remaining part of the applied
waveform.

• Two general categories
• Series
• Parallel

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• Series

• Parallel

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• Biased Clipper circuit

RL
Determine the transition voltage
Step 1
Determine forward reverse biased
Step 2
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Clamping circuit
A clamper is a network constructed of a diode, a
resistor, and a capacitor that shifts a waveform
to a different dc level without changing the
appearance of the applied signal.
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Examples
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Zener diode
A zener diode is a p-n junction device which is
designed for a specific reverse breakdown
voltage.
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Zener effect High reverse voltages can provide
electrons enough energy to jump from valence
band to conduction band, thus creating free
electrons. Hence, the diode conducts a high
current under reverse bias.
Energy band in Silicon Atom
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Avalanche effect Minority carriers in the
depletion region are strongly accelerated by the
electric field, thus creating electron-hole pairs
by impact ionization. The increase of free
carriers increases the current, which provides
more carriers to create impact ionization
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I-V characteristic of zener diode
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Application of Zener Diode

• Zener diode can be used as a voltage regulator
  for providing stable constant reference
  voltages

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Application of Zener Diode (continue)

• Zener diode can be used as a voltage regulator
  for providing stable constant reference
  voltages

Zener diode 1N4740A Izk0.25 mA Power
specification1W Zener impedance is neglected
Maximum and minimum input voltage?
To maintain an approximate 10V output.
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The power specification is 1W. Thus,
For minimum zener current, the voltage across
220? resistor is

Since VR VIN VZ,
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For the maximum zener current, the voltage
across the 220
resistor is,
Therefore,
This shows that this zener diode can ideally
regulate an input voltage from 10.055V to 32V and
maintain an approximate 10V output.
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Application of Zener Diode

• Zener diode can also be used as a clipper

• Zener diode as voltage regulator
• The basic discrete regulator is Zener regulator.

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Exercise 1
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Exercise 2
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Exercise 3
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