Clipping circuits are used to remove the part of a signal that is above or below some defined reference level. To clip to a reference level other than zero, a dc source is put in series with the diode. Depending on the direction of the diode and the polarity of the battery, the circuit will either clip the input waveform above or below the reference level.
Clipping circuits are also known as limiters, amplitude selectors, or slicers.
Clipper Circuit A:
The circuit shown in figure below, clips the input signal above a reference voltage (VR).
In this clipper circuit,
- If Vi < VR, diode is reversed biased and does not conduct. Therefore, Vo = Vi
- If Vi > VR, diode is forward biased and thus, Vo = VR.
The transfer characteristic of the clippers is shown in below figure.
Clipper Circuit B:
The clipper circuit shown in figure below, clips the input signal below reference voltage (VR).
In this clipper circuit,
Clipper Circuit C:
To clip the input signal between two independent levels (VR1 < VR2), the clipper circuit is shown in figure below.
The diodes D1 & D2 are assumed ideal diodes.
For this clipper circuit, when Vi ≤ VR1, Vo = VR1
and, Vi ≥ VR2, Vo = VR2
and, VR1 < Vi < VR2, Vo = Vi
The transfer characteristic of the clipper is shown in figure below.
Clipper Circuit D:
Consider the clipper circuit shown in fig. 1 to clip the input signal above reference voltage
When Vi < (VR + Vr), diode D is reverse biased and therefore, Vo = Vi.
and when Vi > (VR + Vr), diode D is forward biased and conducts. The equivalent circuit, in this case is shown in fig. 2.
The current i in the circuit is given by
The transfer characteristic of the circuit is shown in fig. 3.
Clipper Circuit E:
Consider the clipper circuit shown in fig. 4, which clips the input signal below the reference level (VR).
If Vi > (VR – Vr), diode D is reverse biased, thus Vo = Vi and when Vi < (VR -Vr), D conducts and the equivalent circuit becomes as shown in fig. 5.
Therefore,
The transfer characteristic of the circuit is shown in fig. 6.
Clipper Circuit B:
The clipper circuit shown in figure below, clips the input signal below reference voltage (VR).
In this clipper circuit,
- If Vi > VR, diode is reverse biased. Vo = Vi
- If Vi < VR, diode is forward biased. Vo = VR
Clipper Circuit C:
To clip the input signal between two independent levels (VR1 < VR2), the clipper circuit is shown in figure below.
The diodes D1 & D2 are assumed ideal diodes.
For this clipper circuit, when Vi ≤ VR1, Vo = VR1
and, Vi ≥ VR2, Vo = VR2
and, VR1 < Vi < VR2, Vo = Vi
The transfer characteristic of the clipper is shown in figure below.
Clipper Circuit D:
Consider the clipper circuit shown in fig. 1 to clip the input signal above reference voltage
Fig.1
When Vi < (VR + Vr), diode D is reverse biased and therefore, Vo = Vi.
and when Vi > (VR + Vr), diode D is forward biased and conducts. The equivalent circuit, in this case is shown in fig. 2.
Fig. 2
The current i in the circuit is given by
The transfer characteristic of the circuit is shown in fig. 3.
Fig. 3
Clipper Circuit E:
Consider the clipper circuit shown in fig. 4, which clips the input signal below the reference level (VR).
Fig. 4
If Vi > (VR – Vr), diode D is reverse biased, thus Vo = Vi and when Vi < (VR -Vr), D conducts and the equivalent circuit becomes as shown in fig. 5.
Fig. 5
Therefore,
The transfer characteristic of the circuit is shown in fig. 6.
Fig. 6
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