An additional series resistor in the Wheatstone bridge string (R1) may or may not be required. This is decided

based on the intended output voltage swing for a particular combination of supply voltage, reference voltage,

and the selected gain for an input common-mode voltage range. R1 helps adjust the input common-mode

voltage range, and thus can help accommodate the intended output voltage swing. In this particular example, R1

is not required and can be shorted to ground.

7.2.1.3 Application Curve

Figure 7-5 shows the typical characteristic curve for the circuit in Figure 7-3.

5.0K

5.1K

5.2K

5.3K

5.4K

5.5K

5.6K

5.7K

V(OUT)

V(IN+,IN-)

0V

1.0V

2.0V

3.0V

0V

100mV

200mV

300mV

Bridge Resistance R + ΔR (Ω)

Figure 7-5. Input Differential Voltage, Output Voltage vs Bridge Resistance

INA122

SBOS069A – OCTOBER 1997 – REVISED DECEMBER 2024

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