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07-uhfDistributed - EE 541 Fall 2009 Course Notes#7...

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EE 541, Fall 2009: Course Notes #7 Distributed Circuit Architectures For Analog Signal Processing At Ultra High Frequencies Dr. John Choma Professor of Electrical Engineering University of Southern California Ming Hsieh Department of Electrical Engineering University Park: Mail Code: 0271 Los Angeles, California 90089–0271 213–740–4692 [USC Office] 213–740–8677 [USC Fax] [email protected] ABSTRACT: This technical report details the circuit foundations governing the design and development of quasi-distributed, linear, monolithic amplifiers for broadband analog signal processing applications. Although, these foundations can embrace virtually all solid state device technologies, the implicitly implied focus through- out this report is conventional CMOS technology. As a prelude to documenting a variety of viable circuit topologies for consideration, a review of classic transmission line theory and concepts is provided. Two engineering purposes are served by this review. First, it establishes the propriety of exploiting distributed networks as a practical means of realizing amplifiers for ultra high frequency sys- tem applications. Second, it produces the engineering insights that necessarily underpin the reliable and reproducible realization of quasi-distributed monolithic amplifiers. Original: February 2006
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Course Notes #7 USC Viterbi School of Engineering John Choma August 2006 - 219 - Distributed Networks 1.1.0. BASIC FREQUENCY RESPONSE ISSUES When an integrated electronic signal processor is required to operate at signal frequen- cies extending through the mid-tens of gigahertz, the natural engineering inclination is to select a circuit fabrication process featuring active devices characterized by unity gain frequencies that are a factor of three -to- five larger than the highest signal frequency of interest. Several shortcomings pervade this traditional design methodology. The first and most transparent of these limitations is related to the practical availability and cost effectiveness of available devices. For example, if the highest signal frequency of interest is 40 GHz , the need for devices boasting unity gain frequencies of the order of 175 GHz is apparently dictated. Silicon-germanium (SiGe) heterostructure bipolar technologies are available to deliver this demanding frequency signature, as are numerous III-V compound devices, such as gallium arsenide and indium phosphide metal semiconductor field effect transistors (MESFETs). In the case of SiGe, the availability of suit- able foundries is limited, which bodes increased design and development costs. SiGe circuit realizations also tend toward inefficiency from a static power dissipation perspective, particularly if system requirements mandate amplifiers having large gain-bandwidth products. Moreover, the process traveler for SiGe integrated circuits is a complicated multi-mask process that can signifi- cantly limit integrated circuit yield in the absence of heroic, and therefore time intensive, design and circuit layout measures.
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