hi... i am studying the use of zener diode as clipper.. i saw the following image in wikipedia....
when the input is positive, it is okay..
my doubt is that when the input is negative , won't the zener be forward biased giving rise to only -0.7v in the output , like the following image ??
please help as soon as possible.. i have a test tomorrow.. thanks in advance
Yes you are right zener diode is same as ordinary diode except that it can be operated in reverse biased mode because it is doped differently so that it does not destruct in reverse breakdown. See the pictures below
According to zener reverse bias condition it has a range of voltage in which conduction takes place(values like 4.1,5.2 etc).It will clip the corresponding voltage in its reverse bias condition.
Also it works as ordinary diode in its forward bias.
The image from the Wikipedia article ) is simply wrong. The waveform belongs to a different circuit, not shown in the schematic: a back-to-back series circuit of a zener and a regular diode.