biased clipper

Thread Starter

electronicsbeginner12

Joined Dec 14, 2014
27
Hi. I an confused on how the biased clipper works. I understand the ideal diode acts as a short when forward bias and acts as an open when reversed bias. In the attached image, in figure A, I understand that that the input voltage has to be at least equal to Vb to conduct the ideal diode as shown. But when the diode is reversed in figure B, Im confused on how it produced that clipping at and below positive 4 volts. How can I simplify my analysis? Thanks.
 

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MikeML

Joined Oct 2, 2009
5,444
...In the attached image, in figure A, I understand that that the input voltage has to be at least equal to Vb to conduct the ideal diode as shown.
You said the right words, but drew the wrong picture for A.

But when the diode is reversed in figure B, Im confused on how it produced that clipping at and below positive 4 volts. How can I simplify my analysis? Thanks.
Ask yourself these questions:

If the instantaneous AC Input voltage is less than 4V, what is happening in the diode? If the diode is conducting, what is the output voltage?

What happens if the AC Input voltage is greater than 4V, what is happening in the diode? What controls the output voltage?
 

WBahn

Joined Mar 31, 2012
29,978
I don't see anything wrong with the circuit diagram for (A). If the signal source is above 4V, then the diode will turn on and clamp the output to 4V (for an ideal diode). Your waveform diagram for (A) is ambiguous. Usually the dashed line means a level that is NOT present (usually indicating a level that WOULD have been present if not for the circuit's particular behavior). So you horizontal line at 4V should be solid and the arch above it should be dashed.

Answer MikeML's questions and you will probably understand what is going on.
 

WBahn

Joined Mar 31, 2012
29,978
When you say that your input signal is 5V, is that 5V amplitude? 5V peak-peak? 5Vrms? How are you going from that 5V to a 10V peak signal indicated in your waveform diagram. Same for part (b), only more so since you are saying that your signal is only 3V.
 

Thread Starter

electronicsbeginner12

Joined Dec 14, 2014
27
In my diagrams, the peak voltage is 10 volts, but in my explanations, the input voltages used are just amplitudes occurring at a particular instance in time to explain what happens to Vout when the diode is forward and reverse bias.
 

WBahn

Joined Mar 31, 2012
29,978
There is a disconnect between your circuit diagrams and your waveforms. What is the amplitude of the signal sources in your circuit diagrams?
 

WBahn

Joined Mar 31, 2012
29,978
If you are going to talk about Vt, then you need to define what Vt is. Be sure that ALL of your terms of precisely defined, either in words or via annotations on the diagram.
 
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