Datasheet

ȧ
ȡ
Ȣ
R
g
R
f
)
R
g
R
g
)
R
s
2
ȧ
ȣ
Ȥ
2
(e
ni
)
2
N
A
: Fully Differential Amplifier; termination = 2R
g
Noise
Source
Scale Factor
(i
ni
)
2
R
g
2
(i
ii
)
2
R
g
2
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
ǒ
R
g
R
f
Ǔ
2
4kTR
f
4kTR
g
2
ȧ
ȡ
Ȣ
R
g
R
g
)
R
s
2
ȧ
ȣ
Ȥ
2
N
i
+ 4kTR
s
ȧ
ȧ
ȧ
ȧ
ȡ
Ȣ
2R
t
R
g
R
t
)2R
g
R
s
)
2R
t
R
g
R
t
)2R
g
ȧ
ȧ
ȧ
ȧ
ȣ
Ȥ
2
ȧ
ȡ
Ȣ
R
g
R
f
)
R
g
R
g
)
R
s
R
t
2
ǒ
R
s
)R
t
Ǔ
ȧ
ȣ
Ȥ
2
(e
ni
)
2
N
A
: Fully Differential Amplifier
Noise
Source
Scale Factor
(i
ni
)
2
R
g
2
(i
ii
)
2
R
g
2
2
N =4kTR
i S
2R
G
R +2R
S G
N = (NoiseSource ScaleFactor)S ´
A
4kTR
t
ȧ
ȡ
Ȣ
2R
s
R
G
R
s
)2R
g
R
t
)
2R
s
R
g
R
s
)2R
g
ȧ
ȣ
Ȥ
2
F=1+
N
A
N
I
4kTR
f
2
ǒ
R
g
R
f
Ǔ
2
NF + 10 log (F)
4kTR
g
2
ȧ
ȧ
ȡ
Ȣ
R
g
R
g
)
R
s
R
t
2
ǒ
R
s
)R
t
Ǔ
ȧ
ȧ
ȣ
Ȥ
2
THS4500
THS4501
SLOS350F –APRIL 2002–REVISED OCTOBER 2011 www.ti.com
Scaling Factors for Individual Noise Sources
Asseming No Termination Resistance is Used
(that is, R
T
is Open)
(18)
(19)
(20)
(21)
Figure 111. Noise Sources in a Fully Differential
Amplifier Circuit
Scaling Factors for Individual Noise Sources
(22)
Assuming a Finite Value Termination Resistor
Input Noise With a Termination Resistor
(23)
(12)
Input Noise Assuming No Termination Resistor
(13)
(14)
(24)
Noise Factor and Noise Figure Calculations
(25)
(15)
(26)
(16)
(27)
(17)
30 Submit Documentation Feedback Copyright © 2002–2011, Texas Instruments Incorporated
Product Folder Link(s): THS4500 THS4501