diodes and applications

8/13/2019 Diodes and applications

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Chapter 4Common Diode Applications

Clippers, Clampers, Voltage Multipliers andDisplays


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Diode ClippersA clipper(or limiter) is a circuit used to eliminatesome portion (or portions) of a waveform.

A series clipperis in series with its load.

A shunt clipperis in parallel with its load.


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Series Clippers


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Negative Shunt Clipper Operation


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A Positive Shunt Clipper

SL

L

inLRR

RVV

When the diode is conducting:

When the diode is not conducting:

FL VV


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Biased Shunt Clippers


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Diode Clampers

A clamper(ordc restorer) sets

(or restores) the

dc reference of a

waveform.


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Clamper Operation


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Biased clampersBiased clampersallow a waveform to shifted aboveor below a dc reference other than 0 V.

The dc reference is determined by the biasing voltage (VB)

and the setting of the potentiometer (R1).


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Zener clampersThe diodes in (a) are in a common-cathodeconfiguration.The diodes in (b) are in a common-anodeconfiguration.


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Voltage Doublers A voltage doubler provides an output that is twice its

peak input voltage.


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Half-Wave Voltage Doubler The term half-wave reflects the fact that the

output capacitor (C2) is charges during one

alternation of each input cycle and discharges

during the other.


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Half-Wave Voltage Doubler

Operation


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Full-Wave Voltage Doublers The term full-wave reflects the fact that the

output capacitors are charged during alternatehalf-cycles of the input signal.


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Voltage Tripler A voltage tripler provides a dc output voltage that is

approximately three times the peak input voltage.


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Voltage Quadrupler

A voltage quadrupler provides a dc output voltagethat is approximately four times the peak inputvoltage.


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A Basic Dual-PolarityPower Supply

The output voltages are approximately equal tothe peak values of the input waveform.


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LED Level Indicators

The LED in circuit (a) lights when the driveroutput is +5 V.

The LED in circuit (b) lights when the driver

output is 0 V.


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Multisegment Display

Multisegment displayA device used to displayalphanumeric characters(numbers, letters, symbols,and punctuation marks).

LED displays contain some number of diodes that areconnected in a common-cathode or a common-anodeconfiguration.

A liquid crystal display (LCD)consists of segments thatreflect (or do not reflect) ambient light when providedan active input.


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Seven-Segment Displays

The display uses LEDs that are arranged in a figure 8configuration.

The display represented below is a common-cathode display.Each LED lights when a positive voltage is applied to theappropriate pin.

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