05-Interstage

05-Interstage - EE 541, Fall 2009: Course Notes #5 Passive...

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EE 541, Fall 2009: Course Notes #5 Passive Filter Characteristics and Interstage Matching Networks For Analog RF Integrated Circuits 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] johnc@usc.edu ABSTRACT: Filters play vital roles in the design of RF circuits and systems. Included among these roles are impedance matching to ensure maximum signal power transfer between signal ports and loads imposed on these signal drivers, frequency response shaping to ensure reliable signal detection and the minimization of cumulative electrical noise at RF output ports, and the minimization of extraneous signals or parasitic electromagnetic energy whose frequency spectra lie within the signal processing passband of interest. Yet another function played by a filter is the achievement of nominally constant signal delay between input and output net- work ports. Constant delay looms critical whenever phase distortion is a dominant design consideration. Because RF systems generally operate at very high signal frequencies where active filters have limited magnitude and phase response capa- bilities, most of the filters required of these systems are necessarily passive. Accordingly, this report addresses only passive filter architectures. It begins with a thorough discussion of the characteristics of fundamental RLC networks and proceeds to architectures appropriate to impedance matching. To the latter end, both narrowband and broadband impedance matching are studied. Original: August 2002
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Course Notes #5 University of Southern California John Choma August 2006 149 RF Filters 1.0. INTRODUCTION A major bottleneck underlying the development of high performance analog integrated amplifiers earmarked for radio frequency (RF) applications is the design and implementation of filters required at amplifier input ports, output ports, and interstages. These filters perform one or more of several functions critical to the optimal performance of the communication channels in which the subject RF networks are embedded. One of these functions is impedance matching to ensure the transfer of maximal signal power between driving and loading ports. Such match- ing is essential in ultra high frequency systems where the invariably anemic levels of signal power place input signals at risk of being masked by electrical noise. Filters are also used to shape frequency responses. For example, since the total mean square output noise power of an amplifier is proportional to the 3-dB bandwidth of the amplifier, it is generally prudent to imple- ment a bandpass, as opposed to a lowpass, amplifier frequency response. In this case, the util- ized filter sharply attenuates both low and high frequency energy while preserving nominally constant gain in a frequency passband that is just sufficiently wide to embrace the frequency spectra of the information to be processed.
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05-Interstage - EE 541, Fall 2009: Course Notes #5 Passive...

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