Date of Award

2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Electrical Engineering

First Advisor

Dogan, Numan

Abstract

The Medical Implant Communications Service (MICS) is an ultra-low power, unlicensed, mobile radio service for transmitting data in support of diagnostic or therapeutic functions associated with implanted medical devices. Medical devices that are implanted in the human body have limited size and battery capacity thus requires ultralow power circuitry. Due to the power consumed by the radio transceiver when the system is active, system level power saving techniques such as “sleep mode” is very essential to achieve “low-power”. A wake up receiver (WuRx) is used to detect wireless traffic directed to a node’s receiver and activate it upon detection, without compromising latency and energy dissipation by maximizing data transceiver sleep time. However, the WuRx power consumption must be small compared to the node’s main transceiver because it remains active at all times. Due to the always on nature on the WuRx, it sets a power dissipation floor for the entire system, which requires the receiver design to utilize low-power mixed-signal circuits in the RF front-end and baseband circuit blocks. The WuRx employs various architectural and circuit techniques to minimize power while maintaining an acceptable sensitivity to detect the wake-up signal and preserving data throughput. This thesis explores the specific requirements and challenges for the design of a dedicated wake-up receiver for medical implant communication services equipped with a novel “uncertain-IF” architecture combined with a high – Q filtering MEMS resonator and a free running CMOS ring oscillator as the RF LO. The receiver prototype, implements an IBM 0.18µm mixed-signal 7ML RF CMOS technology and achieves a sensitivity of -62 dBm at 404MHz while consuming <100 µW from a 1 V supply.

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