Oregon State University

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PhD Final Oral Examination – Ronghua Ni


Wednesday, March 20, 2013 3:00 PM - 5:00 PM

Low Power Receivers for Wireless Sensor Networks
Wireless sensor networks increasingly find applications in home automation, environmental monitoring, medical tracking, inventory control and military surveillance. As a sensor node operates on a battery or power harvester for years of lifetime, low power operation is important in the design of the wireless transceiver.

In my first design, a low-power 2.4GHz 1Mb/s hybrid polyphase filter (PPF) based BFSK receiver with ±180ppm frequency offset tolerance (FOT) and 40dB adjacent channel rejection (ACR) at a modulation index (MI) of 2 is presented. High FOT at low MI is achieved by a frequency-to-energy conversion architecture using PPFs without any frequency correction. The proposed hybrid topology of the PPF provides an improved ACR at reduced power. The prototype receiver fabricated in a 0.13μm CMOS process, including RF and analog front-ends, consumes 1.95mW from a 1V supply with -84dBm sensitivity.

My second design presents a 900MHz ultra-low power mixer-less BFSK receiver. A linear RF amplifier with Q-enhanced LC tank is adopted to implement frequency-to-amplitude conversion. This eliminates the need for frequency synthesizer and frequency down-conversion, and improves the interference tolerance. Digitally assisted calibration has been implemented on chip to calibrate the resonant frequency and Q of the LC tank. Fabricated in a 0.13μm CMOS process, the prototype chip consumes 500μW from a 0.7V supply, with a sensitivity of -86dBm and -77dBm for a data rate of 500kb/s and 4Mb/s, respectively.

Co-Major Advisor: Terri Fiez
Co-Major Advisor: Karti Mayaram
Committee: Pavan Hanumolu
Committee: Arun Natarajan
GCR: Michael Olsen 


Kelley Engineering Center (campus map)
1007
Nicole Thompson
1 541 737 3617
Nicole.Thompson at oregonstate.edu
Sch Elect Engr/Comp Sci
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