A 72-nW 440-mV Time Register Using Stacked-NMOS-Switched Gated Delay Cell in Biomedical Applications

This paper presents a time register that uses a gated delay pipeline, to hold or propagate time information through the line by a stacked NMOS switch. The minimum supply voltage can be down to 440 mV, which is much lower than previous state-of-the-arts whose supply voltage is 1 V or higher, making this design beneficial for wearable/implantable devices in biomedical applications. The post-layout simulation performed in 65-nm CMOS technology confirms the function of the proposed time register at a conversion rate of 10 MSamples/s. The stacked-NMOS-switched architecture contributes to low leakage current, realizing low power consumption of 72 nW. In addition, the coefficient of determination, denoted R2, is 0.9956 in the linear input range of 4–11 ns, indicating good linearity.