Amplification of the voltage signal from the Wheatstone
bridge is necessary. Usually, a strain gauge Wheatstone
bridge has 2 mV/V of sensitivity. With the typical 3V of
cell excitation, only 6mV will be available at full scale,
and it requires high amplification. An instrumentation
amplifier is needed with high input impedance, high
differential gain, high common-mode and power supply
rejection ratio, low drift, low offset and low input bias
currents [5]. Meeting these requirements usually results
in low speed performance, but that is not an issue in
the weighing system’s static measurements. Integrated
instrumentation amplifiers can be used since they have
the advantage of internal trimmed resistors for a better
match and increase in overall performance.