Datasheet

e
t
=
4kTR
LMH6654, LMH6655
SNOS956D –JUNE 2001–REVISED MARCH 2013 www.ti.com
Figure 45. Non-Inverting Amplifier Configuration
Figure 46. Inverting Amplifier Configuration
TOTAL INPUT NOISE VS. SOURCE RESISTANCE
The noise model for the non-inverting amplifier configuration showing all noise sources is described in Figure 47.
In addition to the intrinsic input voltage noise (e
n
) and current noise (i
n
= i
n+
= i
n−
) sources, there also exits
thermal voltage noise associated with each of the external resistors. Equation 3 provides the general
form for total equivalent input voltage noise density (e
ni
). Equation 4 is a simplification of Equation 3 that
assumes R
f
|| R
g
= R
seq
for bias current cancellation. Figure 48 illustrates the equivalent noise model using this
assumption. The total equivalent output voltage noise (e
no
) is e
ni
* A
V
.
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