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NF + 10log
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1 )
ǒ
ǒ
e
n
Ǔ
2
)
ǒ
IN+ R
S
Ǔ
2
Ǔ
4 kTR
S
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0
2
4
6
8
10
12
14
16
Source Resistance − Ω
Noise Figure − dB
10 100 1k 10k
G028
f = 10 kHz
T
A
= 25°C
THS4021
THS4022
SLOS265C – SEPTEMBER 1999 – REVISED JULY 2007
Because the dominant noise components are generally the source resistance and the internal amplifier noise
voltage, we can approximate noise figure as:
Figure 32 shows the noise figure graph for the THS402x.
NOISE FIGURE
vs
SOURCE RESISTANCE
Figure 32. Noise Figure vs Source Resistance
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Product Folder Link(s): THS4021 THS4022