Biomedical Engineering Reference
In-Depth Information
Fig. 15 a
S
21
for the original circuit,
b
after addition of
L
D
, and
c
after addition of both
L
D
and
L
C
v
Rg
2
R
g
g
m
v
gs
R
s
i
nd
2
i
out
2
C
aux
i
ng
2
C
gs
v
s
2
L
s
Fig. 16
Noise model for the first stage of designed low-noise amplifier
Furthermore, due to high gain of the first stage, the noise contribution of the
cascode and output stages are much smaller than the first stage. As a result, it is
assumed that the first stage noise is dominant, and only this noise is considered in
calculations. Figure
16
shows a model for the noise of LNA's first stage. Based on
this model,
v
R
g
|
2
2
l
nd
|
2
G
m
(
jω
)
|
+
l
ng
|
T
(
jω
)
|
+
D
(
jω
)
|
F
=
1
+
v
g
|
G
m
(
jω
)
|
2
l
ng
l
nd
T
(
jω
)
D
∗
(
jω
)
+
l
nd
l
ng
D
(
jω
)
T
∗
(
jω
)
+
(5)
v
s
|
G
m
(
jω
)
|
2
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