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PhD Final Exam – Sanket Jain

Integrated receiver architectures tolerant to co-channel and in-band self-interfering blocker signals for MIMO and digital beamforming applications

Simultaneous transmit-and-receive (STAR) radios enable higher spectrum efficiency and dynamic spectrum access. Furthermore, integrating the shared antenna-interface is attractive for small-form factor and MIMO channel estimation. This research focuses on receiver architectures which enable better spectral efficiency by handling blockers in the same spectral range as the signal. The presence of such blockers, without the use of blocker cancelling/filtering techniques leads to gain compression and hence, consequent performance degradation of receivers leading to reduced spectrum efficiency. Two approaches have been devised, implemented in silicon and measured to demonstrate that they alleviate the problems associated with blockers. A system capable of handling co-channel spatially separated blockers is implemented in the first work and another system capable of handling self-interference caused due to the transmitter during full-duplex operation constitutes th! e second work. In the first work, a 4-channel phased array based on a novel architecture incorporating a coupler and a noise-cancelling LNA in combination with a polyphase filter was implemented to eliminate spatial co-channel blockers. This approach allows signal reception from all directions except from the direction of the blocker providing better than 20dB blocker cancellation in the X-band. The second work is aimed at achieving true STAR performance through a hybrid coupler based full-duplex integrated N-path based circulator-Rx architecture. Implemented for frequencies ranging from 550MHz to 900MHz this work addresses the challenge of low-noise wideband self-interference-cancellation by demonstrating a wideband hybrid-coupler circulator antenna interface using N-path mixers that achieves low noise figure while preserving the linearity of passive-mixer first receiver. Better than +5.5dBm power handling of self-interference while providing over 40dB average cancellation! over a bandwidth of 56MHz with a 2.7dB noise figure has been ! measured . Further, the full-duplex circulator architecture has been expanded to a MIMO implementation wherein we demonstrate a 65nm CMOS 2.2GHz 2×2 FD MIMO RX that achieves up to 35/45dB average self-interference-cancellation (SIC) across 40/20MHz BW with more than 42dB/53dB average cross-talk (CT)-SIC across 40/20MHz BW. Interference cancellation mechanisms cause < 2.1dB degradation in RX NF and allows an overall TX power handling of +14dBm enabled by clock bootstrapping.

Major Advisor: Arun Natarajan
Committee: Matthew Johnston
Committee: Thinh Nguyen
Committee: Un-Ku Moon
GCR: William H. Warnes

Tuesday, August 27 at 1:00pm to 3:00pm


Kelley Engineering Center, 1007
110 SW Park Terrace, Corvallis, OR 97331

Event Type

Lecture or Presentation

Event Topic

Research

Organization
Electrical Engineering and Computer Science
Contact Name

Calvin Hughes

Contact Email

calvin.hughes@oregonstate.edu

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