B8 - Section B8 Clippers And Clampers We've been talking about one application of the humble diode rectification These simple devices are also

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Section B8: Clippers And Clampers We’ve been talking about one application of the humble diode – rectification. These simple devices are also powerful tools in other applications. Specifically, this section of our studies looks at signal modification in terms of clipping and clamping . Clippers Clipping circuits (also known as limiters , amplitude selectors , or slicers ), are used to remove the part of a signal that is above or below some defined reference level. We’ve already seen an example of a clipper in the half-wave rectifier – that circuit basically cut off everything at the reference level of zero and let only the positive-going (or negative-going) portion of the input waveform through. To clip to a reference level other than zero, a dc source (shown as a battery in your text) 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 (the battery voltage for an ideal diode; i.e., for V on =0). This process is illustrated in the four parts of Figure 3.43: ¾ Without the battery, the output of the circuit below would be the negative portion of the input wave (assuming the bottom node is grounded). When v i > 0, the diode is on (short-circuited), v i is dropped across R and v o =0. When v i <0, the diode is off (open-circuited), the voltage across R is zero and v o = v i . (Don’t worry; we won’t be doing this for all the circuits!) Anyway, the reference level would be zero. ¾ With the battery in the orientation shown in Figure 3.43a (and below), the diode doesn’t turn on until v i > V B (If this looks strange, revisit the definition of forward bias). This shifts the reference level up and clips the input at + V B and passes everything for v i < V B .
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¾ Figure 3.43b has the battery with the same orientation as in part (a), but the diode has been flipped. Without the battery, the positive portion of the input waveform would be passed (i.e., a reference level of zero). With
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B8 - Section B8 Clippers And Clampers We've been talking about one application of the humble diode rectification These simple devices are also

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