Datasheet

NOISE
e =A ´
O VMAX
2 (R i ) +e +2 4kTR´ ´ ´
S n n S
2 2
(11)
R
F
+V
IN
R
G+
R
G-
-V
IN
FB
R
G
R
S
e
O
VCA824
*
e
O
i
n
4kTR
S
R
S
*
i
n
4kTR
S
NOTE:R andR arenoiseless.
F G
*
*
e
nOUTPUT
i
niOUTPUT
i
inOUTPUT
I
CORE
e
nINPUT
i
nINPUT
R
F
4kTR
F
*
R
S2
4kTR
S2
*
R
F
4kTR
F
e
O
FB
GND
V
OUT
V
REF
V
G
V
G
x1
*
e
nINPUT
i
nINPUT
*
x1
R
G
(Noiseless)
+R
G
-R
G
V-
-V
IN
+V
IN
*
R
S1
4kTR
S1
i
nINPUT
V+
VCA824
www.ti.com ....................................................................................................................................... SBOS394C – NOVEMBER 2007 – REVISED DECEMBER 2008
This model is formulated in Equation 11 and
Figure 89 .
The VCA824 offers 6nV/ √ Hz input-referred voltage
noise density at a gain of +10V/V and 2.6pA/ √ Hz
input-referred current noise density. The
input-referred voltage noise density considers that all
A more complete model is shown in Figure 90 . For
noise terms (except the input current noise but
additional information on this model and the actual
including the thermal noise of both the feedback
modeled noise terms, please contact the High-Speed
resistor and the gain resistor) are expressed as one
Product Application Support team at www.ti.com .
term.
Figure 89. Simple Noise Model
Figure 90. Full Noise Model
Copyright © 2007 – 2008, Texas Instruments Incorporated Submit Documentation Feedback 27
Product Folder Link(s): VCA824