A 65-nm CMOS 1.4-nW Self-Controlled Dual-Oscillator-Based Supply Voltage Monitor for Biofuel-Cell-Combined Biosensing Systems

This paper presents a self-controlled dual-oscillator-based supply voltage monitor for biofuel-cell-combined biosensing systems. First, the proposed self-triggered architecture enables self-control without requiring any external control signals. Second, the proposed frequency subtraction with two gate-leakage-based oscillators with different supply sensitivities enables low-power, small-footprint, and accurate supply voltage monitoring. The proposed supply voltage monitor converts the change in supply voltage into a digital supply voltage code. The proposed supply voltage monitor is fabricated using 65-nm CMOS technology with an active area of 0.0047 mm2, and it shows an operating supply voltage range of 250 mV (0.75-1 V). It consumes a standby power of 1.4 nW at a supply voltage of 0.75 V and has a voltage resolution of 2.4 mV. Furthermore, the measurement results show a peak-to-peak inaccuracy of+12.1 mV/-8.4 mV.