Integrated Readout Circuit Using Active Bridge for Resistive-Based Sensing

Abstract An integrated Readout Interfacing Circuit (ROIC) for resistive-based sensors using SILTERRA CMOS 0.13 μm technology that reads resistance shift and converts it to voltage was designed. In conventional practice, resistive-based sensors are interfaced with Wheatstone bridge to transform the sensor signal to voltage. Due to low sensitivity of Wheatstone bridge, the output voltage of shifted resistance is not significant. The objective of this project is to propose an integrated interfacing circuit using Wheatstone bridge with improved sensitivity. The project scope focuses on integrated circuit design of readout circuitry for resistive-based sensors. An active bridge, a modification of standard Wheatstone bridge using active components was used as ROIC. The sensitivity of the circuit is defined as percentage change in output voltage of the circuit to the changes in resistance of the sensor. Results show that, the active bridge circuit is almost four times more sensitive compare to conventional bridge circuit. The sensitivity improvement would allow any resistive-based sensors to be integrated with ROIC to produce more significant output voltage of shifted resistance.