03-DelayFilter - Course Notes #3 USC Viterbi School of...

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Course Notes #3 USC Viterbi School of Engineering Choma August 2006 - 102 - Delay Filter EE 541, Fall 2009: Course Notes #3 Passive, Constant Resistance, Broadband Delay Filter 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 paper addresses the synthesis of an alternative to the Bessel-Thomson delay filter. The new filter is forged of building blocks familiar to filter designers, while affording the RF designer the luxury of a designable delay that is not inversely dependent on filter bandwidth. Furthermore, the architecture has the desirable attribute of the relative simplicity and low device count that derives from only a second-order realization. In the case of a monolithic realization, excessive chip surface area is therefore not consumed, and the matching error inherent to large numbers of passive devices is minimized. Fi- nally, the new filter has a range of designable delay that is larger than its Bessel- Thomson counterpart due to the purposeful incorporation of right half plane zeros in the transfer function. The paper begins with a tutorial to ensure reader understanding of the building blocks for the proposed filter. The tutorial is followed by a design example. Original: August 2006
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Course Notes #3 USC Viterbi School of Engineering Choma August 2006 - 103 - Delay Filter 1.0. INTRODUCTION In the high performance linear amplifiers, filters, and digital signal processing cells pervasive of modern communication systems, distortionless transmission between the applied signal and resultant output response is an omnipresent engineering goal. “Distortionless” signal transmission is herewith taken to mean that the wave shape of the output response is identical to that of the applied input excitation to within a factor of a multiplicative constant. System output responses that are delayed in the time domain by a constant amount, but otherwise mirror the in- put excitation, are also viewed as distortionless. It follows that the idealized design goal of any linear distortionless network is the assurance that the output response, say y(t) , to an applied in- put signal, x(t) , is given in the steady state by the simple relationship, do y(t) Kx(t T ) , =− (1) where K , the gain of the system, and T do , the time delay implicit to transmitting the input signal to the network output port, are constants. Specifically, K and T do are invariant with the fre- quency spectrum implicit to the input signal, x(t) . While a system projecting the idealized input - to- output (I/O) relationship of (1) is physically unrealizable, specific system applications allow invoking acceptable approximations of the subject relationship. For example, constant I/O delay is relatively unimportant in electronic audio channels because the human ear can readily perceive only signal amplitude fluctuations, thereby rendering constant K far more important than con-
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This note was uploaded on 12/22/2011 for the course EE 541 at USC.

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03-DelayFilter - Course Notes #3 USC Viterbi School of...

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