Continuous monitoring of vital signs, such as respiration and heartbeat, plays a crucial role in early detection and even prediction of conditions that may affect the wellbeing of the patient. Sensing vital signs can be categorized into: contact-based techniques and contactless based techniques. Conventional clinical methods of detecting these vital signs require the use of contact sensors, which may not be practical for long duration monitoring and less convenient for repeatable measurements. On the other hand, wireless vital signs detection using radars has the distinct advantage of not requiring the attachment of electrodes to the subject’s body and hence not constraining the movement of the person and eliminating the possibility of skin irritation. In addition, it removes the need for wires and limitation of access to patients, especially for children and the elderly. This paper presents a thorough review on the traditional methods of monitoring cardio-pulmonary rates as well as the potential of replacing these systems with radar-based techniques. The paper also highlights the challenges that radar-based vital signs monitoring methods need to overcome to gain acceptance in the healthcare field. A proof-of-concept of a radar-based vital sign detection system is presented together with promising measurement results.

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This paper presents a multi-function, dualpolarization phased array transceiver supporting both radar and communication applications at W-band. 32 receive elements and 16 transmit elements with dual outputs are integrated to support 16 dual polarized antennas in a package. The IC further includes two independent 16:1 combining networks, two receiver downconversion chains, an up-conversion chain, a 40GHz PLL, an 80GHz frequency doubler, extensive digital control circuitry, and on-chip IF/LO combining/distribution circuitry to enable scalability to arrays at the board level. The fully-integrated transceiver is fabricated in the IBM SiGe BiCMOS 0.13um process, occupies an area of 6.6X6.7mm 2 , and operates from 2.7V (analog/RF) and 1.5V (digital) supplies. Multiple operating modes are supported including the simultaneous reception of two polarizations with a 10GHz IF output, transmission in either polarization from an IF input, or single-polarization transmission/reception from/to I&Q base-band signals (2.5W RX, 2.9W TX). Measurement results show 8dB receiver NF and 2dBm transmitter output power per element at 94GHz in both polarizations.

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Abstract-A 17 GHz low-power radio transceiver front-end implemented in a 0.25 m SiGe:C BiCMOS technology is described. Operating at data rates up to 10 Mbit/s with a reduced transceiver turn-on time of 2 s, gives an overall energy consumption of 1.75 nJ/bit for the receiver and 1.6 nJ/bit for the transmitter. The measured conversion gain of the receiver chain is 25-30 dB into a 50 load at 10 MHz IF, and noise figure is 12 0.5 dB across the band from 10 to 200 MHz. The 1-dB compression point at the receiver input is 37 dBm and IIP 3 is 25 dBm. The maximum saturated output power from the on-chip transmit amplifier is 1.4 dBm. Power consumption is 17.5 mW in receiver mode, and 16 mW in transmit mode, both operating from a 2.5 V supply. In standby, the transceiver supply current is less than 1 A.Index Terms-BAW resonator, energy/bit, energy efficiency, low-power radio, radio transceiver front-end, SiGe BiCMOS technology, wireless sensor networks.

Adaptable communication systems are of great interest as they provide dynamic front end to accommodate the tunable spectrum management in advanced wireless systems. Memristor (acronym of memory resistor) is an emerging technology part of resistive RAM (RRAM) that has good potential for application in reconfigurable RF devices. The potentiality of using resistive switches for frequency tuning of high frequency RF filters is successfully explored in this article for the first time. Tunable RF filter is designed with detailed simulation using Ansys HFSS, and then correlated with measured results from experiment. As a proof of concept, a prototype of the tunable RF filter is fabricated by using a graphene oxide (GO) integrated with a conventional microstrip open stub notch filter. The resistor switching ability of the device is exploited for the frequency tuning. The resonating length of the notch filter is varied by changing the resistance of the active GO material between ‘HIGH’ (OFF) and ‘LOW’ (ON) resistance states. The measured results demonstrate the great potential of using RRAM in tunable RF devices. It also proves the possibility of tuning RF devices without any localized surface mount device (SMD) element or complex realization technique.