Wake-up radios have been a popular transceiver architecture in recent years for battery-powered applications such as wireless body area networks (WBANs) [1], wireless sensor networks (WSNs) [2,3], and even electronic toll collection systems (ETCS) [4]. The most important consideration in implementing a wake-up receiver (WuRX) is low power dissipation while maximizing sensitivity. Because of this requirement of very low power, WuRX are usually designed by a simple RF envelope detector (RFED) consisting of Schottky diodes [1,3] or MOSFETs in the weak inversion region [2] without active filtering or amplification of the input signal. Therefore, the performance of the RFED itself is critical for attaining good sensitivity of the WuRX. Moreover, the poor filtering of the input signal renders the WuRX vulnerable to interferers from nearby terminals with high transmit power such as mobile phones and WiFi devices, and this can result in false wake-ups [1]. Although the RFED has very low power, a false wake-up will increase the power consumption of the wake-up radio as it will enable the powerhungry main transceiver.An RF SAW filter can be used in front of the RFED to reduce false wake-ups [2], but it has wider bandwidth in the GHz range and is not sufficient to reject interferers. Furthermore, its insertion loss degrades sensitivity. A narrowband BPF also can be used to remove interference after the RFED [3]. However, it is usually implemented by a passive R-C filter due to the requirement of low power, and also has poor selectivity [1,2]. To overcome these challenges of WuRX, a low-power, high-gain RFED and a low-power delay-based BPF (DBPF) that has a narrow and sharp frequency response that is sufficient to reject interferers are newly proposed in this paper. The IC reported here is a fully integrated wake-up radio for ETCS compliant with the GB/T 20851-2007 Chinese dedicated shortrange communication (DSRC) standard [4].
Seok-Oh YUN †a) , Jung Hoon LEE † †b) , Nonmembers, Jin LEE † † †c) , Member, and Choul-Young KIM †d) , Nonmember SUMMARY Real-time monitoring of heart rate (HR) and body temperature (BT) is crucial for the prognosis and the diagnosis of cardiovascular disease and healthcare. Since current monitoring systems are too rigid and bulky, it is not easy to attach them to the human body. Also, their large current consumption limits the working time. In this paper, we develop a wireless sensor patch for HR and BT by integrating sensor chip, wireless communication chip, and electrodes on the flexible boards that is covered with non-toxic, but skin-friendly adhesive patch. Our experimental results reveal that the flexible wireless sensor patch can efficiently detect early diseases by monitoring the HR and BT in real time.
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