MEMS Transceiver Satisfies Low-And Medium- Data-Rate Uses

WIRELESS AND NETWORKING capability have not been seamlessly integrated into tiny devices for short-distance wireless applications. Such low-datarate (LDR) applications, which typically operate at 10 kb/s, include wireless sensor networks (WSNs) and wireless body-area networks (WBANs). Also suffering from this lack of integration are 1-Mb/s medium-data-rate (MDR) applications, such as audio streaming, medical devices, miniature drug delivery systems, and implants. Currently, LDR and MDR both use different radios that are optimized for each application. A single miniature radio that covers all LDR and MDR applications was proposed by the Swiss Center for Electronics and Microtechnology's David Ruffieux, Jrmie Chabloz, Matteo Contaldo, Claude Mller, Franz- Xaver Pengg, Paola Tortori, Alexandre Vouilloz, Patrick Volet, and Christian Enz.

The researchers used a combination of high-Q microelectromechanical-systems (MEMS) devices, such as RF bulk-acoustic-wave (BAW) resonators and filters, together with a low-power RF integrated circuit (RF IC). The dedicated radio architecture employs a fixed-frequency, high-Q BAW RF oscillator while tuning at the intermediate frequency (IF). Based on a BAW digitally controlled oscillator (DCO) and a variable IF local oscillator (LO) obtained by fractional division from the RF carrier, the synthesizer displays phase noise of 113 dBc/ Hz at 3 MHz offset from the carrier. At 100 kb/s, sensitivity of 87 dBm is reached for overall power consumption of 6 mA. To demonstrate a high-datarate, quasi-direct one-point modulation capability, the transmitter generates a 4 dBm, 1-Mb/s GFSK signal with an overall current of 20 mA. See "A Narrowband Multi-Channel 2.4 GHz MEMS-Based Transceiver," IEEE Journal Of Solid-State Circuits, January 2009, p. 228.

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