A 20 μ W, 0.05mm2 Duty-Cycled Resistor and Frequency-Locked-Loop-based Wheatstone Bridge Interface for Low Resistance Sensing Systems

The growing need for ubiquitous, ultra-low-power sensors has driven continuous advancement in low-power performance and energy efficiency for read-out circuits, with broad applications in environmental sensing of temperature / humidity and barometric pressure. In these sensor architectures, a Wheatstone bridge circuit provides balanced readout. While this approach is efficient for large sensor resistance (5k0-500k0), measuring small resistance (<;1k0) with low power consumption presents a fundamental challenge that is increasingly necessary for a growing class of sensors for strain and force in wearable devices and robotics.