الأربعاء، 27 ديسمبر 2017

Two Way Parallel Clipper Circuit

      
       In this circuit it is required to clip the portions of both positive and negative half cycles of the input. For this clipping at two different levels is required.
Note: Combining positive and negative clipper circuits with VR, a two way parallel clipper can be obtained.
       The circuit diagram of two way parallel clipper is shown in the Fig 1.
Fig 1 two way parallel clipper
       Assume that the input is purely snusoidal in nature.
                      Vin = Vm sinωt
       The diodes D1 and D2 are ideal diodes.
1.1 Operation
       Positive half cycle of the input: When Vin goes positive till it becomes more than V1, D1 and D2, both the diodes are reverse biased. And Vo= Vin
       When Vin >V1, then D1 becomes forward biased and conducts. While D2 remains reveres biased for the entire positive half cycle of the input. This shown in the Fig 2 (a) and (b).
Fig 2 positive half cycle of input
       Thus when Vin < V1, D1 and D2 are OFF and Vo=Vin
       While when Vin > V1, D1 is ON D2 is OFF and Vo=V1
       Negative half cycle of the input : In the negative half cycle, as long as Vin is greater then V2, the diode D2 remains reverse biased. The D1 remains OFF for the entire negative half cycle of the input. This is shown in the Fig 3(a). The Vo= V2 .
Fig. 3 negative half cycle of input
       When Vin becomes less than V2, the diode D2 becomes forward biased and conducts. The diode D1 is still OFF. This is shown in the Fig 3 (b) where Vo= V2. The output Vo is negative as the polarities of V2 are opposite to that of V1.
Fig 4 waveforms for two way parallel clipper
The input and output waveforms for the two way clipper are shown in the Fig 4.
 1.2 Transfer Characteristics
       The mathematical equations for the two way clipper are,
       The transfer characteristics are shown in the Fig 5.
Fig 5 transfer characteristics for two way parallel clipper
Note : Thus the circuit clips the input for both positive as well as negative half cycles and hence called two way parallel clipper circuit.

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