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Cucumber Guy
Cucumber Guy • Mar 28, 2008

Designation of a negative clamping circuit. please help.

Input Square Wave is described as follow:
V max : 20V
V min : -15v
Frequency : 10kHz

Design a clamper circuit to shift its referecence point so that its reference point is -10V.
Specify all component values and part numbers(if any) used in your design. Show all calculation clearly. Justify any assumption made.

That was the question given. I want to know that in negative clamping this wave so that its reference point goes down to 10v, what should be done? like what should increase or what should decrease? additional capacitors? dont have to give me the specific value but please help me by telling me the rough idea of where i should start and what i should be looking for or notice. Please help me with this as i am totally lost. thank you so much!!
pratik_ghatwai • Apr 2, 2008
i think .........there is nothin to do with just add the 30 volt battery in your circuit............then you will find your circuit giving you -10 v..............and see the working of clamper circuit in any book,,,,,,you ll b able to kno why i m telling you to add 30v battery below th diode used ,.
mkaras • Jun 8, 2008

Your clamping circuit can be built using a concept as I'll describe. You'll select a capacitor to AC couple your 20V to -15V signal @ 10KHz into the clamp circuit. The clamp circuit itself can be built a couple of ways. One simple way is to use a diode if absolute accuracy is not your ultimate goal. The diode is connected cathode to the output side of your AC coupling capacitor and the anode side is connected into a circuit that has a voltage level approximately one diode drop above the clamp level that you wish to attain. In operation the charge across the AC coupling capacitor adjusts so that the output only swings down to the -10V level. You have to select the AC coupling capacitor so that it is big enough to permit the 10KHz signal to pass through the circuit without significant attenuation. LTSpice is a handy free program to help evaluate circuits like this.
mkaras • Jun 8, 2008

Hi mate,refering to your waveform it is clamping both V+ and V-,by 4volts can u explain??,as far as i know it shud clamp only negative voltage
mkaras • Jun 11, 2008
I am clamping the negative peak of the signal to a specific level without attempting to change the amplitude of the signal. In order to clamp only one level and leave the other peak the same as the input in terms of its absolute voltage level then one must start with a DC coupling of the signal.
so ur clamping an AC signal,ok,i thought u were clamping DC signal,anyhow then it ok!!

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