{"id":717,"date":"2010-06-25T12:12:53","date_gmt":"2010-06-25T16:12:53","guid":{"rendered":"https:\/\/wpmu2.mit.local\/?p=717"},"modified":"2010-07-27T11:03:59","modified_gmt":"2010-07-27T15:03:59","slug":"ultra-low-power-transceivers-for-body-area-networks","status":"publish","type":"post","link":"https:\/\/wpmu2.mit.local\/ultra-low-power-transceivers-for-body-area-networks\/","title":{"rendered":"Ultra-low-power Transceivers for Body-area Networks"},"content":{"rendered":"
\"Figure<\/a>

Figure 1: The proposed prototype system. The entire system (minus the antenna) is in a single package, and internal wirebonds are used to connect the BAR die to the CMOS chip.<\/p><\/div>\n

The rise of on-body medical monitoring devices has created a need to efficiently and securely transmit physiological information around the body.\u00a0 As opposed to wired-links, wireless Body-area Networks (BANs) provide a comfortable and unobtrusive communication medium for this information at the expense of energy and security.\u00a0 The principal challenge in radio design for BANs is a tight power budget.\u00a0 To address this issue, we are investigating new RF architectures that use high-Q MEMS devices [1<\/a>]<\/sup> in low-power RF filters and oscillators for integration into a prototype transceiver system..<\/p>\n

High-Q front-end filtering permits the exploration of unconventional ultra-low-power receiver architectures whereby downstream power requirements can be relaxed.\u00a0 The aim of this project is to integrate a high-Q Bulk Acoustic Resonator (BAR) device near the beginning of the receiver chain as an extremely narrowband channel-select filter.\u00a0 The signal can then undergo a power-efficient down-conversion followed by a simple energy-detection at an uncertain intermediary frequency [2<\/a>]<\/sup>.<\/p>\n

\"Figure<\/a>

Figure 2: Schematics of the transmitter (top) and receiver (bottom).<\/p><\/div>\n

For body-worn nodes, an RF transmission power of around -10 dBm is sufficient to cover short distances of 1-2 m.\u00a0 However, designing very efficient systems for such low RF output power is a challenge.\u00a0 Very high-Q resonators can be used as low-power local oscillators with excellent stability and precision [3<\/a>]<\/sup>, obviating the need for an energy-hungry PLL.\u00a0 Optimized push-pull amplifier strategies are also employed along with energy-efficient modulation schemes like BPSK and OOK. \u00a0Pulse shaping, realized by modulating the matching network to the PA, is used to improve spectral usage and thus increase data-rates.<\/p>\n

In both the transmit and receive paths, a variable center-frequency is required to utilize all channels within the 2.4 GHz ISM band. \u00a0For this, our architecture utilizes multiple resonators spaced at different frequencies.\u00a0 The entire radio front-end (minus the antenna) can be integrated into a single-package prototype, and internal wirebonds can be used to stitch the resonators to the circuits.<\/p>\n

\r\nReferences
  1. R. Marathe, A. Erbes, D. Weinstein, “RF-MEMS resonators for body-area network transceivers<\/a>,” Massachusetts Institute of Technology, Cambridge, MA, MTL Annual Research Report, 2010. [↩<\/a>]<\/li>
  2. N. M. Pletcher, S. Gambini, and J. M. Rabaey, “A 2GHz 52 \u03bcW Wake-Up Receiver with -72dBm Sensitivity Using Uncertain-IF Architecture,” ISSCC 2008. Digest of Technical Papers,<\/em> pp.524-633, 3-7 Feb. 2008. [↩<\/a>]<\/li>
  3. Y. H. Chee, A. M. Niknejad; and J. M. Rabaey, “A sub-100 \u03bcW 1.9-GHz CMOS oscillator using FBAR resonator,” Radio Frequency Integrated Circuits (RFIC) Symposium, 2005, <\/em>pp. 123- 126, 12-14 Jun. 2005. [↩<\/a>]<\/li><\/ol><\/div>","protected":false},"excerpt":{"rendered":"

    The rise of on-body medical monitoring devices has created a need to efficiently and securely transmit physiological information around the…<\/p>\n<\/div>","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[26,27],"tags":[17,4060,4061],"_links":{"self":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts\/717"}],"collection":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/comments?post=717"}],"version-history":[{"count":5,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts\/717\/revisions"}],"predecessor-version":[{"id":2310,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts\/717\/revisions\/2310"}],"wp:attachment":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/media?parent=717"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/categories?post=717"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/tags?post=717"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}