Network Impedance
The total equivalent impedance of a multi-branch sensor network dictates the current draw and signal amplitude in precision measurement circuitry. Correctly balancing the bridge resistance ensures that the differential output voltage remains zero at the null point.
Thermal Behavior
Self-heating in resistive elements represents a major source of measurement error in transducer applications. If the bridge resistance is too low, excessive excitation current raises the temperature of the strain gauges, which induces thermal drift and shifts the zero point. Designers calculate the excitation voltage based on this value to maintain the sensor within its thermal budget.
Calibration Reference
Adjustment of the output offset involves adding high-precision shunt resistors across specific arms of the circuit. In high-reliability instrumentation, the nominal bridge resistance is measured under zero-load reference conditions to establish a baseline for subsequent calibration cycles. This baseline measurement is verified at the factory using a four-terminal setup to eliminate test lead effects.
Error Contribution
Impedance mismatch between the sensor branches generates common-mode signals that can saturate downstream instrumentation amplifiers. Because bridge resistance changes over time due to mechanical stress or aging, periodic ratiometric tests are required. These verification steps are conducted at pre-determined intervals using certified reference standards.
