Novel method for balancing full wheatstone bridge for high-tolerance resistive sensors

Abstract

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Wheatstone bridge (WB) is widely used in precision measurements involving strain gauges and resistive sensors. However, maintaining balance in a full-bridge configuration becomes increasingly challenging in the presence of high-resistance tolerances—especially in printed electronics, where such variations are common. Traditional compensation methods often entail increased circuit complexity, added cost, and additional sources of error. This article proposes a novel balancing technique for fully resistive WBs, leveraging two voltage References to cancel the output offset even in the presence of resistor tolerances exceeding 0.1%. The method demonstrates robust performance with tolerance levels up to 20%, while preserving high linearity. Simulation results confirm that the approach achieves balanced operation and accurate output even with low-tolerance resistors (1%). Relative to the ideal sensitivity of (VCC-VEE) , the proposed technique maintains a worst-case sensitivity of 0.8 (VCC-VEE) , with a theoretically null output offset under balanced conditions. Furthermore, linearity error remains below 0.5% of the full-scale output (FSO), matching the performance of conventional WB circuits affected by mismatch. While the resolution of the voltage references introduces a small, predictable offset—independent of power supply variations—this error is limited to the resolution of the reference itself. Experimental validation using benchtop instrumentation corroborates the simulation findings: with resistors exhibiting 10% tolerance, the maximum deviation between measured and theoretical outputs was 2.4 mV. This deviation remains negligible in terms of estimating fractional resistance changes.

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