Reconfigurable Passive Mixer-First Receivers

مرکز و کتابخانه مطالعات اسلامی به زبان های اروپایی

منو

" Reconfigurable Passive Mixer-First Receivers "
Wilson, Charley Theodore Shahzad, Muhammad

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1106439
Doc. No	:	TLpq2393699951
Main Entry	:	Shahzad, Muhammad
	:	Wilson, Charley Theodore
Title & Author	:	Reconfigurable Passive Mixer-First Receivers\ Wilson, Charley TheodoreShahzad, Muhammad
College	:	North Carolina State University
Date	:	2019
student score	:	2019
Degree	:	Ph.D.
Page No	:	149
Abstract	:	Passive mixer-first receivers are a potential solution for the challenge of developing a universal wideband receiver to meet the exponentially increasing demand in mobile wireless communications systems. Tunable center frequency and passivity of the mixer between RF and baseband are fundamental in allowing the receiver to accommodate multiple communication bands without the need for large external components in a single hardware solution. The key challenges addressed in this work are (1) understanding and exploiting the passivity of the mixer at harmonic frequencies, (2) extension of the baseband coupling network to realize a multi-port receiver, and (3) extension of mixer operating frequency to its fundamental limits. The first key contribution in this research is circuits and theory for passive mixer-first receivers with circulant-symmetric baseband coupling networks. Current approaches do not utilize off-axis feedback paths in the baseband network of a passive mixer. This work aims to understand the possible performance enhancements that can be gained by controlling the harmonic behavior of the mixer through these additional paths. A linear time-invariant (LTI) model of the mixer has been developed and verified in simulation and in hardware with an eight-phase receiver with circulant-symmetric baseband network. The second key contribution is circuits and theory for coupling multiple receiver to create a reconfigurable multiple-input and multiple-output (MIMO) receiver with adaptable multi-port matching network. Information theoretic optimization of a multi-port matching network has potential capacity benefits. Passivity of the passive mixer enables a baseband network to tune the input impedance and we will also introduce coupling in the baseband between receivers to achieve multi-port matching at radio-frequency (RF). The theory and circuit model introduced have been verified with simulations and a hardware demonstration of a two-port eight-phase passive mixer-first receiver. Performance of a two-port receiver has been demonstrated using a real-time 2×2 MIMO communication system resulting improved capacity with optimization of the multi-port input impedance. The receiver performance was compared using coupled and un-coupled antennas with single and multi-port adaptive matching techniques.Measurements show a 7 dB improvement in signal-to-noise ratio (SNR) with closely spaced antennas and optimized baseband multi-port coupling. The third key contribution is development and demonstration of high-frequency wideband receivers. The challenge of generating non-overlapping clock pulses for driving passive mixer switches is addressed through AND-ing the pules with CMOS transmission gates. Two generations of the receiver have been designed and fabricated with variation in the differential quadrature clock generation circuit. The first-generation prototype uses a narrowband on-chip passive network and operates from 20-30 GHz. This is the first known demonstration of a N-path mixer above 12 GHz. The second-generation introduces a high-frequency divider with quadrature outputs enabling operation down to 3 GHz. The application of high-frequency passive mixer-first receivers is evaluated with a comparison to a traditional LNA-first receiver at 28 GHz.
Subject	:	Electrical engineering