Design and Experimental Verification of A 2.1 nW 0.018 mm~2 Slope ADC-Based Supply Voltage Monitor for Biofuel-Cell-Powered Supply-Sensing Systems in 180-nm CMOS

摘要

This brief presents a slope analog-digital converter (ADC)-based supply voltage monitor (SVM) for biofuel-cell-powered supplysensingsystems operating in a supply voltage range of 0.18–0.35 V. Theproposed SVM is designed to utilize the output of energy harvesterextracting power from biological reactions, realizing energy-autonomoussensor interfaces. A burst pulse generator uses a dynamic leakagesuppression logic oscillator to generate a stable clock signal under the subthresholdregion for pulse counting. A slope-based voltage-to-timeconverter is employed to generate a pulse width proportional to the supplyvoltage with high linearity. The test chip of the proposed SVM isimplemented in 180-nm CMOS technology with an active area of 0.018mm2. It consumes 2.1 nW at 0.3 V and achieves a conversion time of 117–673 ms at 0.18–0.35 V with a nonlinearity error of ?5.5/+8.3 mV, achievingan energy-efficient biosensing frontend.