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Title:Wideband direct conversion IQ modulators in indium phosphide DHBT technology
Author(s):Iverson, Eric
Director of Research:Feng, Milton
Doctoral Committee Chair(s):Feng, Milton
Doctoral Committee Member(s):Rosenbaum, Elyse; Gong, Songbin; Schutt-Ainé, José E.
Department / Program:Electrical & Computer Eng
Discipline:Electrical & Computer Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Indium Phosphide
Double Heterojunction Bipolar Transistor
IQ Modulator
Quadrature Modulator
Abstract:High performance instrumentation has seen major benefits from custom integrated circuits in an indium phosphide double-heterojunction bipolar transistors (InP DHBT) (Low et al. 2005). The highest speed oscilloscopes that are currently available rely on InP DHBT circuits in their frontend and enable a combination of high peak-to-peak voltage and high sampling rate that is not possible using a silicon CMOS or silicon-germanium based frontend (Pupalaikis et al. 2014). Due to their extensive success in instrumentation, it was a worthwhile experiment to determine what performance enhancements might be seen in IQ modulator circuits using an InP DHBT process. During the course of investigating this question, I focused on designing a direct conversion IQ modulator that could be useful across the full bandwidth of existing vector signal generators and also extend that bandwidth beyond the current state of the art. I employed a circuit architecture in which the limiting factor for modulator bandwidth was the device switching time, which enabled modulation across carrier frequencies from 50 MHz to 26 GHz, a more than 3x increase in bandwidth compared to other IQ modulators covering the cellular band. Chapter 1 of this work provides an introduction to IQ modulation and an overview of the function of the IQ modulator in its target application. In Chapter 2, the broadband IQ modulator design is presented. Chapter 3 covers the benchmarking measurements of the IQ modulator. Chapter 4 details the re-design effort, which focused on increasing the linearity of the modulator. Chapter 5 concludes and summarizes this work. Appendix A presents original work on extraction of minority carrier mobility in the base region of InP DHBTs.
Issue Date:2015-01-21
Rights Information:Copyright 2014 Eric Iverson
Date Available in IDEALS:2015-01-21
Date Deposited:2014-12

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