Datasheet

10
100 1k 10k
FREQUENCY (Hz)
1
10
100
INPUT VOLTAGE NOISE DENSITY
(nV/
Hz)
GAIN = 1000
GAIN = 500
GAIN = 250
GAIN = 100
GAIN = 51
GAIN = 10
1
10 100 1000
CLOSED LOOP GAIN (V/V)
0
4
8
12
16
20
24
INPUT VOLTAGE NOISE DENSITY (nV/
Hz)
V
S
= 5V
f = 100 Hz
LMP2021, LMP2022
SNOSAY9E –SEPTEMBER 2008–REVISED MARGH 2013 www.ti.com
Figure 39. Input Voltage Noise Density decreases with Gain
Figure 40 shows the input voltage noise density does not have the 1/f component.
Figure 40. Input Voltage Noise Density with no 1/f
With smaller and smaller input signals and high precision applications with lower error budget, the reduced input
voltage noise and no 1/f noise allow more flexibility in circuit design.
ACHIEVING LOWER NOISE WITH FILTERING
The low input voltage noise of the LMP2021/LMP2022, and no 1/f noise make these suitable for many
applications with noise sensitive designs. Simple filtering can be done on the LMP2021/LMP2022 to remove high
frequency noise. Figure 41 shows a simple circuit that achieves this.
In Figure 41 C
F
and the corner frequency of the filter resulting from C
F
and R
F
will reduce the total noise.
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