Supply Method
Power supply method for resistive sensor networks that maintains a fixed amperage regardless of resistance fluctuations in the bridge. Utilizing constant current bridge excitation improves linearity in piezoresistive sensors compared to traditional voltage-driven circuits. The output voltage of the bridge becomes proportional to the change in resistance rather than a more complex ratio.
This simplifies the mathematical model used for signal processing.
Lead Compensation
Long cable runs between the sensor and the electronics introduce parasitic resistance. Because constant current bridge excitation forces a set amperage through the entire loop, the voltage drop across lead wires does not affect the measurement accuracy. This makes the technique ideal for remote monitoring in industrial environments.
Thermal Regulation
Thermal regulation depends on power dissipation staying consistent. Self-heating errors are predictable under constant current bridge excitation.
Metrological Advantage
Sensitivity variations caused by temperature changes in the bridge resistors are partially offset by the properties of the current source. In many silicon sensors, the temperature coefficient of sensitivity is negative while the temperature coefficient of resistance is positive. Using constant current bridge excitation allows these two effects to cancel each other out to some degree.
This reduction in thermal span error lowers the burden on the compensation software. Measurements remain stable even as the sensor temperature fluctuates during operation.
