Dissertation Defense

Energy-efficient Wireless Circuits and Systems for Internet of Things

Jaeho Im


As the demand of ultra-low power (ULP) systems for internet of things (IoT) applications has been increasing, there have been significant efforts on reducing the power of wireless radios to connect these devices. Most ULP radios reported today, however, are not standard compliant which poses a challenge to widespread adoption. For example, being compliant with the WiFi network protocol can maximize an ULP radio’s potential of utilization. This standard demands excessive power consumption though, well over 10mW, which is hardly compatible with ULP systems even with heavy duty-cycling. In addition, minimizing the number of off-chip components in ULP IoT devices helps to reduce cost and form-factor. In particular, off-chip crystal oscillators are bulky and expensive compared to CMOS chips, but eliminating the crystal is especially challenging to do while keeping the device associated with a wireless network.

This research is focused on radio designs for IoT applications with a focus on low active power, standard compliance to enable widespread adoption, minimizing the number of off-chip components, and small form factor. The research presents three prototypes as power-efficient WiFi wake-up receivers, which bridge the gap between industry standard radios and ULP IoT radios. The proposed WiFi wake-up receivers operate with low power consumption while listening to an existing 802.11 transmitter by changing the firmware, or more specifically just the data in the payload of the WiFi packet. In this work, low power mixer-first receivers, and the first fully integrated ultra-low voltage receiver are presented. In addition to prototypes of WiFi wake-up receivers, a reference-less fully-integrated 60GHz transceiver co-designed with an on-chip antenna is presented small form-factor IoT applications.

Chair: Professor David D. Wentzloff

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