EE 541 addresses the analysis, design, and implementation of high performance analog filters suit-able for data processing, information transmission, and radio frequency (RF) communication systems realized in modern monolithic circuit technologies. Several reasons underlie the necessity of suitable filters in these systems. Foremost among these reasons is that they can be used to match or otherwise modify circuit impedances to ensure the reasonably efficient transfer of signal power between driver and load ports. Maximum power transfer is a critical design objective in high frequency communica-tion networks because the anemic levels of signal power indigenous to such systems increase the risk of contaminating signal information content by omnipresent electrical noise. Filters can also be em-ployed to improve the high frequency responses of active circuits by mitigating the deleterious impact of active device capacitances. They can even improve the observable linearity of certain types of ac-tive systems through a sharp attenuation of the high frequency harmonics incurred by inherent active device nonlinearities. The RC and RLC filters implicit to electronic power supplies comprise simple examples of filters designed to obviate undesirable harmonics of power line frequencies. Finally, fil-ters can annihilate unwanted signals by offering designable frequency selectivity. For example, low-pass filters all but eliminate undesired signal or noise energy at very high frequencies, bandpass fil-ters offer frequency selective signal processing, as well as a reduction of cumulative output noise en-ergy, and stopband filters obviate the energy of specific frequencies lying within the frequency spectra of signal information earmarked for processing.
Active filters comprised of resistors, capacitors, and either operational amplifiers (op-amps) or op-erational transconductor amplifiers (OTAs) are widely used in audio, video, and other types of rela-tively low frequency signal processors. But for systems operating in the high hundreds of megahertz -to- the tens of gigahertz, active filters are inappropriate because of the inadequate gain-bandwidth product, phase response, delay characteristics, and linearity metrics afforded by op-amps and OTAs. As a result, passive filtering networks containing resistors, capacitors, inductors, and even transform-ers and distributed transmission lines are commonplace in RF and ultra high frequency mixed signal integrated circuits. Indeed, and in stark contrast to more traditional very large scale integrated (VLSI) digital circuits, these monolithic RF units display a relatively high ratio of passive -to- active components. These latter (passive) filters comprise the dominant focus of EE 541.
The fundamental theories that underpin the design and realization of passive filters were largely forged four -to- six decades ago by such technical luminaries as Cauer, Chen, Darlington, Foster, Huelsman, Mitra, and others. One course is not a sufficient forum to address all of these seminal contributions. But since an insightful understanding of relevant circuit theoretic concepts is essential to the meaningful and efficient design of passive filters for RF systems, EE 541 does address essential theoretic issues. Included among these issues are two port networks, scattering analyses, parametric sensitivity, and distributed network analyses. The latter analyses are pivotal for a satisfying under-standing of very high frequency circuit dynamics, and they form the basis for the design of distributed passive and active networks offering exciting I/O transfer characteristics, impedance matching, delay, and high frequency compensation attributes. The design strategies entailing impedance matching, broadband compensation, frequency response selectivity, and other types of filters are addressed de-finitively.
