Wireless Systems Lab

May 2018 — New Members — Paul Danker will be joining the Wireless Systems Lab as an undergraduate researcher for the Summer of 2018. He will be helping with visible light communication projects.
May 2018 — ISCAS Paper — Yifei Li's paper "Time-domain analysis of optimum bias point in inverse class-F power amplifier" will be presented at this year's IEEE Intl. Symposium on Circuits and Systems held in Florence, Italy. This paper discusses new insights into the effect of different bias points on the overall efficiency of Class-F^-1 power amplifiers.
May 2018 — I²MTC Paper — Subhanwit Roy's paper "Coaxial microwave resonant sensor design for monitoring ionic concentration in aqueous solutions" will be presented at this year's IEEE Intl. Instrumentation and Measurement Technology Conference held in Houston, Texas. This paper discusses various passive microwave sensors for detecting nutrient concentrations in farm water samples.
January 2018 — New Members — We would like to welcome two new members with the Wireless Systems Lab: Scott Melvin and Subhanwit Roy. Scott is pursuing his M.S. degree and will be working on wireless energy harvesting. Subhanwit will be pursuing his PhD and will be working in the area of reconfigurable RF circuit design.

May 2017 — ISCAS Paper Presentation — Byron Montgomery's paper "Analysis and Utilization of Planar Baluns for Dual-Band Push-Pull Power Amplifiers" at this year's IEEE International Symposium on Circuits and Systems held in Baltimore, MD in May. This paper details new balun architectures suitable for use in dual-band push-pull power amplifiers.
April 2017 — Graduation — Congratulations to Yifei Li for successfully defending his PhD. Yifei's thesis titles was "Development of High-Efficiency Switch-Mode Concurrent Dual-Band Power Amplifiers." His research focused on developing new theoretical descriptions of switch-mode power amplifiers operating at multiple carrier frequencies, simultaneously. Using this theory, he designed and implemented the first reported concurrent dual-band class-D power amplifier which achieved an impressive 60% drain efficiency. After graduation Yifei will be joining MaxLinear in Carlsbad, CA.
April 2017 — Graduation — Congratulations to Byron Montgomery for successfully completing his M.S degree in Electrical and Computer Engineering. Byron's thesis title was "Common Mode Termination Requirements in Concurrent Dual-Band Push-Pull Power Amplifiers." His research focused on exploring new balun architectures and design requiresments for use in push-pull power amplifiers operating at multiple carrier frequencies, simultaneously. After graduation, Byron will be joining Rockwell Collins in Cedar Rapids, IA.

October 2016 — Teaching Award — Dr. Nathan Neihart has been awarded the Deptment of Electrical and Computer Engineering's Warren B. Boast Undergraduate Teaching Award.
June 2016 — Dr. Neihart to Serve as Associate Editor for IEEE TCAS-II — Starting June 2016, Dr. Neihart will begin serving as an Associate Editor for IEEE Trans. on Circuits and Systems Part-II: Express Briefs (TCAS-II). TCAC-II is a monthly publication focusing on rapid disseination of original, timely, and significant contributions to the research community. More information can be found at the IEEE Circuits and Systems Society Publications Webpage.
April 2016 — WAMICON Paper Presentation — Yifei Li's paper "Development of a concurrent dual-band switch-mode power based on current-switching class-D configuration," will be presented at this year's IEEE Wireless and Microwave Technology Conference held in Clearwaterwater Beach, FL in April. This paper details the first dual-band class-D power amplifier to date. The full citation can be found here.
April 2016 — Journal Paper Accepted — Yifei Li's paper "Switchless compact dual-band matching networks for class-E power ampliviers," has been accepted for publication in Analog Integrated Circuits and Signal Processing. This article compares two methods for realizing non-concurrent dual-band load networks suitable for class-E power amplifiers, an LC-based approach and a newly proposed transformer-based approach. The full citation can be found here.

July 2015 — Graduation — Congratulations to Zhen Zhang whom successfully completed his Master of Science degree. Zhen's thesis title was "Comparison Between Single-Band and Concurrent Multi-Band Linear RF Power Amplifiers" and focused on quantifying the fundamental differences in the efficiency of concurrent dual-band RF power amplifiers as compared to their single-band counterparts.

June 2015 — New Research Grant — Dr. Neihart's proposal "A New Design Paradigm for Switch-Mode Power Amplifiers Supporting Concurrent Multi-Band Wireless Communication" was awarded $300,000 from the National Science Foundation to begin in August of 2015. This research will provide a detailed understanding of the design trade-offs in concurrent multi-band power amplifiers and a new set of design techniques enabling RF designers to address the challenge4s posed by next generation wireless system design.

May 2015 — Graduation — Congratulations to Titus Rotich whom successfully completed his Master of Science degree. Titus's project title was "Dual Band Radio Frequency Energy Harvesting with Single Matching Network" and focused on the development of a dual-band energy harvester capable of simultaneously harvesting energy from the 2.4 and 5.2 GHz bands.

May 2015 — MWSCAS Paper Presentation — Zhen Zhang's paper "Architecture comparison for concurrent multi-band linear power amplifiers" will be presented at this year's IEEE Midwest Symposium on Circuits and Systems in Ft. Collins, Co. in August. This paper presents a quantitative comparisson between concurrent multi-band and parallel single-band power amplifier architectures in an effort to determine which applications can benefit from concurrent multi-band power amplifiers and which applications should continue to utilize the conventional solution for parallel single-band power amplifiers.The full citation can be found here.

May 2015 — ISCAS Paper Presentation — Amany El Gouhary's paper "A quadrature oscillator for LTE/LTE-A standards with an improved quadrature- mode stability" will be presented at the 2015 Int. Symposium on Circuits and Systems. This paper introduces a quadrature oscillator for LTE/LTE-A standards with an improved quadrature mode stability using transformers. The full citation can be found here.

Apr. 2015 — MTT Paper Published — Kossi Sessou's paper "An integrated 700-1200 MHz class-F PA with tunable harmonic terminations in 0.13um CMOS" was published in the April 2015 edition of IEEE Trans. on Microwave Theory and Techniques. This paper presents a fully integrated class-F power amplifier with reconfigurable harmonic termination over a wide range of frequencies. The full reference can be found here.

Feb. 2015 — New Research Grant — Dr. Nathan Neihart received $495,000 from the United States Department of Agriculture to develop hand-held sensors for the detection of harmful cyanotoxins in fresh water sources.

Sep. 2014 — Xiaohua Yu's paper "A transformer-based dual-coupled triple-mode CMOS LC-VCO" has been published in the the September 2014 edition of IEEE Trans. on Microwave Theory and Techniques. This paper introduces a transformer-based, dual-coupled, VCO using a transformer-based 4th-order tank with tunable transconductance feedback between the primary and secondary coils.

Aug. 2014 — The Wireless Systems Lab welcomes Sara Neshani, Jayaprakash Selvaraj, and Byron Montgomery. Sara and Jayaprakash will be pursuing their PhD degrees and Byron will be pursuing his MS degree.

Aug. 2014 — Yifei Li's paper "Switchless matching networks for dual-band class-E power amplifiers," was invited for presentation at the 2014 Midwest Symposium on Circuits and Systems in College Station, TX. This paper presented two different switchless dual-band load networks for concurrent dual-band class-E power amplifiers. The full citation can be found here.

July 2014 — Amany El Gouhary's paper "An analysis of phase noise in transformer-based dual-tank oscillators," has been published in the July 2014 issue of IEEE Trans. on Circuits and Systems I. This paper introduces a new phase noise analysis technique for one- and two-port dual-mode transformer-based oscillators. The full citation can be found here.

May 2014 — Congratulations to Amany El-Gouhary on her successful completion of her PhD. Her thesis title was "Methods and techniques for improving figure-of-merit for wide tuning range quadrature voltage controlled oscillators." Also, congratulations to Kossi Sessou whom successfully completed his Master of Science degree. Kossi's thesis title was "Design of a class-F power amplifier with reconfigurable output harmonic termination in 0.13um CMOS."

May 2013 — Congratulations to Xiaohua Yu on his successful completion of his PhD. His thesis title is "Reconfigurable Multi-Mode RF Circuits."

May 2013 — Our paper "Analysis and design of a reconfigurable multi-mode low-noise amplifier utilizing a multi-tap transformer," was among the top 10 most downloaded papers for MTT in the month of March 2013.

May. 2013 — Yifei Li's paper "Mathematical analysis of inter-band intermodulation for concurrent dual-band mixers," was presented at the 2013 Intl. Symposium on Circuits and Systems. This work presented a detailed analysis of the nonlinear effects in concurrent multi-band mixers including inter-band as well as intra-band intermodulation. The full citation can be found here.

Mar. 2013 — Xiaohua Yu's paper "Analysis and design of a reconfigurable multi-mode low-noise amplifier utilizing a multi-tap transformer," was invited to appear in the March 2013 IEEE Trans. on MIcrowave Theory and Techniques Speical Issue on 2012 RFIC Symposium. This paper expanded upon the reconfigurable low-noise amplifier presented in 2012 RFIC by including detailed analysis and design guidelines. The full citation can be found here here.

Sep. 2012 — Amany El Gouhary's paper "Inductor-based tuning in LC-quadrature oscillators: a comparative study" was publisehd in the September 2012 issue of Trans. on Circuits and Systems II. This paper examined three different methods for injecting a tuning current into the tank of current-tuned oscillators. It was shown that, depending upon the method for injecting current into the tank, a trade-off between tuning range, phase noise, and power conusmption exists. The full citation can be found here.

Aug. 2012 — Congratulations to Jeremy Brown on his successful completion of his Master of Science degree. His thesis title was "Design of a Magnetically Tunable Low Noise Amplifier in 0.13um CMOS Technology."

May 2012 — The Wireless Systems Lab welcomes Yifei Li. He will be joining in Fall 2012 to pursue his Ph.D. degree.

Nov. 2012 — Our paper "A dual-band 2.45/6 GHz CMOS LNA utilizing a dual-resonant transformer-based matching Network" has been published in the August 2012 edition of Trans. on Circuits and Systems I. This paper describes a new transformer-based matching network for realizing area efficient dual-band low noise amplifiers. The full citation can be found here.

June 2012 — Dr. Neihart will begein serving on the Analog Signal Processing Technical Committee of the IEEE Circuits and Systems Society. This committee focuses on the theory, analysis, design, and practical implementaiton of analog integrated circuits, and the application of analog circuit thoery to system and signal processing, ranging from basic scientific theory to industrial applications.

Feb. 2012 — Xiaohua Yu's paper "A 2-11 GHz reconfigurable multi-mode LNA in 0.13um CMOS" was presented at the 2012 IEEE Radio Frequency Integrated Circuits Symposium in Montreal.This paper presents a reconfigurable multi-mode low-noise amplifier capable of single band, concurrent dual-band, and ultra-wideband operation. The full citation can be found here.