Datasheet

Scaling Factors for Individual
(e )
ni
2
2
R
G
R +
G
R
S
2
R
G
R
F
+
(18)
(i )
ni
2
R
G
2
(19)
(i )
ii
2
R
G
2
(20)
2
4kTR
F
2 ´
R
G
R
F
(21)
N
i
N
A
R
g
R
f
e
g
e
f
e
s
R
s
e
n
N
o
i
ni
i
ii
R
t
e
t
N
i
S
i
N
o
S
o
+
−
fully-diff
amp
R
g
R
f
e
g
e
f
2
4kTR
G
2 ´
R
G
R +
G
R
S
2
(22)
Scaling Factors for Individual
N
i S
=4kTR
R +
S
2R
T G
R
R
T G
+2R
2R
T G
R
R
T G
+2R
2
(23)
(e )
ni
2
2
R
G
R +
G
R
S
R
T
2( )R +R
S T
R
G
R
F
+
(12)
N
i S
=4kTR
2R
G
R
S G
+2R
2
(24)
(i )
ni
2
R
G
2
(13)
Noise Factor and Noise Figure Calculations
(i )
ii
2
R
G
2
(14)
N = (NoiseSource ScaleFactor)S ´
A
(25)
F=1+
N
A
N
I
(26)
NF=10log(F)
(27)
R +
T
2R
S G
R
R
S G
+2R
2R
S G
R
R
S G
+2R
2
4kTR
F
(15)
2
4kTR
F
2 ´
R
G
R
F
(16)
4kTR
G
2
R
G
R +
G
R
S
R
T
2( )R +R
S T
2 ´
(17)
THS4504
THS4505
www.ti.com ......................................................................................................................................................... SLOS363D – AUGUST 2002 – REVISED MAY 2008
Noise Sources Assuming No Termination
Resistance is Used (for example, R
T
is open)
Figure 88. Noise Sources in a Fully
Differential Amplifier Circuit
Input Noise With a Termination Resistor:
Noise Sources Assuming a Finite
Value Termination Resistor
Input Noise Assuming No Termination Resistor:
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