Datasheet

NOISE FIGURE
vs
SOURCE RESISTANCE
18
14
0
20
16
12
Noise Figure – dB
R
s
– Source Resistance – Ω
10 100 1k 10k
T
A
= 25°C
8
4
10
6
2
NF + 10log
ȧ
ȧ
ȧ
ȧ
ȧ
ȱ
Ȳ
1 )
ȧ
ȡ
Ȣ
ǒ
e
n
Ǔ
2
)
ǒ
IN ) R
S
Ǔ
2
ȧ
ȣ
Ȥ
4 kTR
S
ȧ
ȧ
ȧ
ȧ
ȧ
ȳ
ȴ
NF + 10log
ȧ
ȧ
ȱ
Ȳ
e
2
ni
ǒ
e
Rs
Ǔ
2
ȧ
ȧ
ȳ
ȴ
THS6012
www.ti.com SLOS226F –SEPTEMBER 1998–REVISED JUNE 2012
Because the dominant noise components are generally the source resistance and the internal amplifier noise
voltage, we can approximate noise figure as:
Figure 42 shows the noise figure graph for the THS6012.
Figure 42. Noise Figure vs Source Resistance
Copyright © 1998–2012, Texas Instruments Incorporated 21