Unformatted text preview: lable from the source (Pav,source /Pav,load . Find the
expression for Ga using signal ﬂow graph approach. Is Ga a function of source
impedance? Is Ga a function of load impedance?
(d) Under what situation will GT = Gp = Ga ?
(e) Under what situation will GT = |S21 |2 ?
5. (a) Consider a common-source ampliﬁer with its small-signal model shown below.
Find its [S ] as a function of rg , Cgs , gm , ro , Cds . Verify your results with
simulation using the following parameters at 1 GHz: rg = 10 ohm, Cgs = 50 fF,
gm = 10 mS, ro = 1k ohm, Cds = 25 fF.
(b) Find Γin if load is a 1nH inductor. Find Γout if source is a 25 ohm resistor.
2 1. Consider the common-source ampliﬁer shown below. The source and load impedances
are both 50Ω. The transistor parameters are: Cgs = 50f F , rg = 10Ω, gm = 80mS ,
ro = 50Ω and Cds = 30f F . rg
- gmVgs ro Cds (c) Simulate Γin from 1 - 20 GHz when the ampliﬁer is loaded with RLC parallel
tank (R = 628 ohm, L = 1nH, C = 200fF).
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- Fall '09
- Impedance, Input impedance, Electrical impedance, Impedance matching, Impedance bridging, load impedance