NCS325, NCS2325, NCS4325

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10

Differential Amplifier for Bridged Circuits

Sensors to measure strain, pressure, and temperature are

often configured in a Wheatstone bridge circuit as shown in

Figure 24. In the measurement, the voltage change that is

produced is relatively small and needs to be amplified before

going into an ADC. Precision amplifiers are recommended

in these types of applications due to their high gain, low

noise, and low offset voltage.

Figure 24. Bridge Circuit Amplification

+

−

VDD

VDD

GENERAL LAYOUT GUIDELINES

To ensure optimum device performance, it is important to

follow good PCB design practices. Place 0.1

mF decoupling

capacitors as close as possible to the supply pins. Keep traces

short, utilize a ground plane, choose surface−mount

components, and place components as close as possible to

the device pins. These techniques will reduce susceptibility

to electromagnetic interference (EMI). Thermoelectric

effects can create an additional temperature dependent

offset voltage at the input pins. To reduce these effects, use

metals with low thermoelectric−coefficients and prevent

temperature gradients from heat sources or cooling fans.