In this paper, we present a portable SOS device with wireless communication. This device is based on all-digitalphase-locked-loop (ADPLL). A wake-up mode is implemented for low power consumption. With extra biological sensors attached to the users, the device is awakened by abnormal signals and actively sends a SOS signal for help. Moreover, it can use those sensors to collect information from users. This information can be modulated to RF frequency and sent out along with the SOS signal. The SOS device also can be used in passive mode with a SOS button in some emergency situations.
A low-power coarse-fine time-to-digital converter (TDC) with a wide dynamic range and high time resolution is presented in this paper. The first stage is based on a buffer delayline chain. Then the input signal and its adjacent reference clock are injected into a Vernier-delay-line (VDL) time-quantizer at the second stage for a finer resolution. The proposed architecture can provide high resolution with less hardware compared to the one-stage VDL TDC with the same dynamic range. A powersaving circuit is employed achieving >50% power reduction. A delay-tunable buffer is utilized to tolerate the process, voltage and temperature (PVT) variations. The design's parameter has been simulated and optimized in a 65nm CMOS process. The simulation results show a minimum time resolution of 6.15 ps and a maximum dynamic range of 1260 ps corresponding to 8bits resolution. The power consumption is 2.5 mW with the reference frequency of 40MHz.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.