9 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification, and TI

does not warrant its accuracy or completeness. TI’s customers are responsible for determining

suitability of components for their purposes. Customers should validate and test their design

implementation to confirm system functionality.

9.1 Application Information

9.1.1 Filter Pin

The INA848 allows access between the two amplification stages. In applications surrounded from high input

noise, adding filter stages can be of high benefit. Figure 9-1 and Figure 9-2 show two different filter scenarios

that help filter out undesired differential signals.

9.1.1.1 RC Filter Network

In environments where known high-frequency noise must be eliminated, use a low-pass filter containing a

capacitor, and optionally, a resistor.

G = 200

6 k

120 k

6 k

6 k

120 k

6 k

C

FL

V

DIFF

+FL

FL

+

–

+IN

IN

R

L

Low-Pass Filter

OUT

REF

INA848

Figure 9-1. Low-pass Filter

The ‒3-dB cross frequency is determined given following equation:

f

FL1

=

1

(2)

Where 6 kΩ represents the internal resistor network. Use the Analog Engineer's Calculator for fast and easy

bode plot visualization.

9.1.1.2 RLC Filter Network

In environments where a known, narrow-frequency band must be attenuated, a series LC filter network can be

added between the filter pins, as shown in Figure 9-2. The connection adds to the internal resistor network, and

results in a RLC filter network that is also commonly known as bandstop filter.

G = 200

6 k

120 k

6 k

6 k

120 k

6 k

C

FL

V

DIFF

+FL

FL

+

–

+IN

IN

R

L

Band-Stop Filter

OUT

REF

L

FL

INA848

Figure 9-2. Bandstop Filter

Use Equation 3 to calculate the middle frequency of the filter:

1

(3)

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INA848

SBOS946 – SEPTEMBER 2020

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