Chap-4 Diode Circuits

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Chapter -4 Diode Circuits

Prepaid By: Prof . Vishal Mishra

Assistant Prof. in E&C Department

Marwadi Education foundation

Prof. Vishal Mishra

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SJTU Zhou Lingling 2

Half-Wave Rectifier

(a) Half-wave rectifier.

(b) Equivalent circuit of the half-wave rectifier with the diode replaced with itsbattery-plus-resistance model.

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SJTU Zhou Lingling 3

Half-Wave Rectifier

(c)Transfer characteristic of the rectifier circuit.

(d) Input and output waveforms, assuming that RrD

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SJTU Zhou Lingling 4

Full-Wave Rectifier

(a) Circuit(b) Transfer characteristic assuming a constant-voltage-drop model for the

diodes

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5

Full-Wave Rectifier

(c)input and output waveforms.

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6

The Bridge Rectifier

(a)Circuit

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SJTU Zhou Lingling 7

The Bridge Rectifier

b)

Input and Output waveforms

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The circuit for a positive clamper isshown in the figure. During thenegative half cycle of the inputsignal, the diode conducts and actslike a short circuit. The outputvoltage V

o

0volts . The capacitoris charged to the peak value of inputvoltage V

m. and it behaves like a

battery. During the positive half ofthe input signal, the diode does notconduct and acts as an open circuit.

Hence the output voltage Vo

Vm+Vm This gives a positively clampedvoltage.

Vo Vm+ Vm= 2 Vm

Diode :- Clamper

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Diode :- Clamper

Positive Clamper

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Diode :- ClamperNegative Clamper

During the positive half cycle the diodeconducts and acts like a short circuit. Thecapacitor charges to peak value of inputvoltage V

m. During this interval the output

Vowhich is taken across the short circuit

will be zero During the negative half cycle,the diode is open. The output voltage canbe found by applying KVL.

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Diode :- Clamper

Negative Clamper

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Diode :- Clamper

Biased Clamper

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Diode :- Clamper

The circuit of a positively biased clamperis shown in the figure. During thenegative half cycle of the input signal the diode is forward biased and acts like ashort circuit. The capacitor charges to Vi+ Vs . Applying the KVL to the input side

During the positive half cycle of the input signal, the diode is reverse biased and itacts as an open circuit. Hence V

shas no effect on V

o. Applying KVL around the

outside loop.

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ClippersCLIPPERS AND LIMITERS

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Clipping removes part of the positive or negative peaks of a signal or both.Silicon diodes do not conduct until the applied voltage exceeds about 0.6volts and only when the anode is positive with respect to the cathode.

The circuit is like a potential divider with the diode part being highresistance for voltages below 0.6 volts and low resistance above.

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Reference

SJTU Zhou Lingling

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