THS4021_16 Datasheet, PDF (11/29 Pages) Texas Instruments – 350-MHz LOW-NOISE HIGH-SPEED AMPLIFIERS

THS4021
THS4022
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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:
ǒ Ǔ ^ȱ
NF + 10log^{ȧȧȧȧ}1 )
ǒ ǒenǓ² ) IN+
4 kTRS
Ǔ²
RS
ȳ
ȧȧȧȧ
Ȳ
È´
Figure 32 shows the noise figure graph for the THS402x.
NOISE FIGURE
vs
SOURCE RESISTANCE
16
f = 10 kHz
14 ^TA ^{= 25°C}
12
10
8
6
4
2
0
10
100
1k
10k
Source Resistance − Ω
G028
Figure 32. Noise Figure vs Source Resistance
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