A 2.4-GHz BAW-Based Transceiver for Wireless Body Area Networks

This paper presents a BAW-based transceiver targeting wireless networks for biomedical applications. The use of high-Q microelectromechanical-systems resonators brings interesting benefits to the fundamental building blocks of the frequency synthesis, receiver, and transmitter and allows achieving at the same time low-power consumption, improved phase noise, and high selectivity in the receiver and transmitter paths. In the baseband, the power consumption is minimized thanks to the use of a phase analog-to-digital converter (ADC) which directly quantizes the phase of the received signal instead of using two separate amplitude ADCs. A complete wireless node composed of the transceiver integrated circuit (IC) and a microprocessing IC, both integrated in a standard digital 0.18-μm complementary metal-oxide semiconductor technology are described and validated by measurement results. The RF carrier phase noise is -136.2 dBc/Hz at 1-MHz offset. The transmitter demonstrates 1-Mb/s Gaussian frequency-shift keying modulation at an output power of 5.4 dBm with an overall current of 35 mA, in compliance with Bluetooth and Bluetooth low energy output spectrum requirements. At the receiver, further investigations are needed to find the origins of an unexpected sensitivity of -75 dBm at 200 kb/s.