Electronic Devices - FET Amplifiers - Discussion
Discussion Forum : FET Amplifiers - General Questions (Q.No. 9)
9.
Referring to this figure, calculate Av for yos = 58 
S.
S. 
Discussion:
8 comments Page 1 of 1.
Tayyab said:
3 years ago
Here, Av=-gm(RD//Rd).
Millize said:
4 years ago
To get the exact value of Av, first you would need to solve for Vgsq:
Solving for Vgsq convert the circuit by using Thevenin's theorem where Vth = 18(10M/(10M+110M)) = 1.5 V.
Rth = 10M//110M.
Using KVL on the gate-source loop of the new circuit:
1.5 -IgRth-Vgsq-IdRs = 0
Since Ig=0 and Id = Idss(1-Vgs/Vp)^2 then substituting.
1.5 -0-Vgsq-(Idss(1-Vgsq/-3)^2)(150) = 0.
Vgsq = 0.367 V.
Solving for gm, where gm = gmo(1-Vgsq/Vp) = (2Idss/|Vp| )(1-Vgsq/Vp),
gm = 4.48 mS,
Av = -gm(Rd//rd) ; rd = 1/Yos,
Av = -7.3.
Solving for Vgsq convert the circuit by using Thevenin's theorem where Vth = 18(10M/(10M+110M)) = 1.5 V.
Rth = 10M//110M.
Using KVL on the gate-source loop of the new circuit:
1.5 -IgRth-Vgsq-IdRs = 0
Since Ig=0 and Id = Idss(1-Vgs/Vp)^2 then substituting.
1.5 -0-Vgsq-(Idss(1-Vgsq/-3)^2)(150) = 0.
Vgsq = 0.367 V.
Solving for gm, where gm = gmo(1-Vgsq/Vp) = (2Idss/|Vp| )(1-Vgsq/Vp),
gm = 4.48 mS,
Av = -gm(Rd//rd) ; rd = 1/Yos,
Av = -7.3.
(1)
Ano Nymous said:
5 years ago
@Gabbo.
yos = (1/rd).
yos = (1/rd).
Gabbo said:
6 years ago
How to get rD? please. Help!
SHIVU said:
6 years ago
gm = 2IDSS/VP.
AV = -GM(rD//RD).
AV = -GM(rD//RD).
Jean said:
9 years ago
The formula is 2 * IDSS/|Vp|.
(1)
Rowell said:
10 years ago
@Pedro.
How to get gm for this?
How to get gm for this?
Pedro said:
1 decade ago
Av = -gmRD.
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