Thought of the Day

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Thought of the Day

• HAPPINESS is found in
• the process of achieving,
• not merely in
• POSSESING.

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Clippers and Clampers - 1

• D.C. Kulshreshtha

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Topics to be discussed

• What is a Clipper Circuit ?
• General characteristic of a double clipper.
• Series negative clipper.
• Processing by series negative clipper.
• Series Biased Clippers.
• Guidelines to Solve.
• Numerical Examples.

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Clippers

• A circuit that clips off or removes a portion of
  the input signal.
• A clipper can process any type of signal.

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Upper Limiting level
General characteristic of a double clipper.
Upper threshold point
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• There can be single clippers
• Positive
• Negative
• Two categories
• Series Diode and load in series.
• Parallel Diode and load in parallel.

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Series negative clipper
The circuit
The transfer characteristics
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Processing by series negative clipper
Square wave
Draw the output.
Triangular wave
Draw the output.
This clipper is like a half-wave rectifier.
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Rectangular wave or Square wave ?
Ans. Both are same. Usually, we call it a square
wave.
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What happens if the diode in a half-wave
rectifier is reversed ?
Ans. It still remains a half-wave rectifier, but
it now works as a positive clipper.
Input
Output ?
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Series Biased Clippers

• Bias means applying a dc voltage to change the
  dc level of a circuit.

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Guidelines to Solve

• Determine the transition level at which the diode
  turns ON.
• With diode ON, find relation between vo and vi.
• Draw the transfer characteristic of the clipper.
• Plot the waveshape of vo for given input.

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We find that

• Diode is ON for vi gt VB.
• Therefore, vi(tr) VB.
• When diode is ON, vo vi VB.
• When diode is OFF, vo 0.
• Plot the transfer characteristic of the clipper.

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Characteristic (Graph between input and output)
Draw the output wave corresponding to a
sinusoidal input with Vm gt VB
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Now, draw the output.
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Example 1

• Determine the output waveform for the clipper
  circuit, if the input is a sinusoidal wave of
  peak value 15 V.

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Solution

• The direction of the diode suggests that it will
  be ON for positive values of vi.
• At transition level,

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• After diode is ON,

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Transfer characteristic
Draw the output.
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Example 2

• Determine the output waveform for the clipper
  circuit of Example 1, if its input is as follows

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Solution
Problem is simpler. Only two levels vi 15
V and vi -5 V
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Now, you can draw the output.
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Note that

1. Total swing of vi is 15 (-5) 20 V.
2. Total swing of vo is 18 0 18 V.
3. Clipper circuit clipped off 2 V, and raised the
   dc level by 3 V.