Clippers:
In the clipper circuits, discussed so far, diodes are assumed to be ideal device. If third approximation circuit of diode is used, the transfer characteristics of the clipper circuits will be modified.
Clipper Circuit 4:
Consider the clipper circuit shown in fig. 1 to clip the input signal above reference voltage
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Fig. 1
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Fig. 2
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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.
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Clipper Circuit 5:
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 condcuts and the equivalent circuit becomes as shown in fig. 5.
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Fig. 4
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Fig. 5
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Therefore,
The transfer characteristic of the circuit is shown in fig. 6. |
Fig. 6
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