Differential Input Voltage (V)

0

0.2

0.4

0.6

0.8

1

-100

-50

0

50

100

150

200

250

IB+

IB-

Figure 9-2. Input Bias Current vs Differential Input Voltage

The measurement error expected from the additional external filter resistors can be calculated using Equation 1,

where the gain error factor is calculated using Equation 2.

Gain Error (%) = 100

(100

Gain Error Factor)

-

´

(1)

The gain error factor, shown in Equation 1, can be calculated to determine the gain error introduced by the

additional external series resistance. Equation 1 calculates the deviation of the shunt voltage resulting from the

attenuation and imbalance created by the added external filter resistance. Table 9-1 provides the gain error

factor and gain error for several resistor values.

S

3000

Gain Error Factor

R

3000

(2)

Where:

• RS is the external filter resistance value

Table 9-1. Gain Error Factor and Gain Error For External Input Resistors

EXTERNAL RESISTANCE (Ω)

GAIN ERROR FACTOR

GAIN ERROR (%)

5

0.998

0.17

10

0.997

0.33

100

0.968

3.23

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INA240

SBOS662C – JULY 2016 – REVISED DECEMBER 2021

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