# amplitude modulation explain

Discussion in 'Homework Help' started by mrmike612, Dec 13, 2012.

1. ### mrmike612 Thread Starter New Member

Dec 1, 2012
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if anyone knows please explain for me,my modulating signal is square from 0-5v
the voltage of square with vbias,how does it work to affect the vgs.
how do i have to choose vbias to make sure it works on reverse-biased

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2. ### WBahn Moderator

Mar 31, 2012
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Since this is YOUR homework, you need to show what efforts you have made thus far to solve it. We can then look over what you have done right, what you have done wrong, and find a way to get you back on track and moving a bit further down the road.

3. ### mrmike612 Thread Starter New Member

Dec 1, 2012
11
0
hmm....okay....I have some confusions about vbias so I need to make it clear first.I'm not asking for solutions,I'm asking for explaination because i got stuck at my idea.
My thought was ...square wave fluctuates between 0-5v and to make jfet works as voltage resistor control,we should make Vgs<Vp because the maximum resistance shows at Vgs=vp
But when we have square and vbias at the same time.how do i identify the voltage Vgs.Thats what I m' confused

4. ### mrmike612 Thread Starter New Member

Dec 1, 2012
11
0
My problem is calculate the proper vbias to make the circuit has the smooth modulation

5. ### crutschow Expert

Mar 14, 2008
12,522
3,064
Since there is so much variation between FETs I expect you will have to experimentally determine the best bias point for that circuit for the particular transistor you have.

Apr 26, 2005
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