Electronic Devices - FET Amplifiers - Discussion
Discussion Forum : FET Amplifiers - General Questions (Q.No. 60)
60.
Refer to this figure. If VGS = –6 V, calculate the value of RS that will provide this value.
2.2 k
1.2 k
600 k
100 k
Discussion:
4 comments Page 1 of 1.
Adel said:
3 years ago
But the Vgs is greater than Vgs off. So the current id should be 0!
Ano Nymous said:
5 years ago
@Oliver Pogs I think it's 50K as well. I don't know why they divided IDSS by 2?
Oliver Pogs said:
6 years ago
I think it should be 15k ohm?
From gm0 we can compute Vp:
gm0 = (2*Idss)/|Vp|.
Vp = -5 V (Since N channel jfet).
Then we compute Id:
Id = (10m)(1- (-6/-5))^2.
Id = 400 uA.
Rs = VGS/Id = 6/400uA.
Rs = 15 k ohms.
From gm0 we can compute Vp:
gm0 = (2*Idss)/|Vp|.
Vp = -5 V (Since N channel jfet).
Then we compute Id:
Id = (10m)(1- (-6/-5))^2.
Id = 400 uA.
Rs = VGS/Id = 6/400uA.
Rs = 15 k ohms.
Brindha said:
8 years ago
Id = IDSS/2 ,10mA/2=5mA.
VGS=-ID * RS, -6V= -(5mA) * RS.
RS = -6V/-5mA,
RS= 1.2k.
VGS=-ID * RS, -6V= -(5mA) * RS.
RS = -6V/-5mA,
RS= 1.2k.
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