A 480 fJ/conversion-step 13-bit Resistive Sensor Readout IC with a 1%/V Power Supply Sensitivity

Conventional resistive sensor readout ICs (ROICs) suffer limitations, either because of their high resistive sensor-biasing current consumption or low resolution for jitter-induced noise. To overcome these limitations, a 13-bit resistive sensor ROIC is presented in this work. In the proposed ROIC, which relies on zero-crossing-based circuits (ZCBCs), the current source is used not only to settle the output of the ΔΣ integrator, but also to bias the resistive sensor, and thus avoid implementing a dedicated power-hungry bias current branch. In addition, the oversampled ΔΣ modulation technique guarantees high resolution for the proposed ROIC. A prototype was fabricated using 0.18 μm CMOS technology. The measurement results show the ROIC achieved a 13-bit root-mean-square noise equivalent resolution with an 8 kS/s conversion speed and a 480 fJ/conversion-step figure of merit. Moreover, it has good nonlinearity of less than 250 ppm and a power supply sensitivity of 1%/V.