Analytical Circuit Model Extraction for Robot Automatic Tuning of Microwave Filtering Networks Prof. Ke-Li Wu Dept. of Electronic Engineering, The Chinese University of Hong Kong |
Abstract: Filtering network is a compulsory device in a communication system. Its performance decisively determines signal-to-noise ratio, interference rejection and loss dispersion of a transmitter/receiver system. Metal-cavity-type filters, due to their high Q characteristic, are dominantly used in wireless infrastructure equipment and presently their manufacturing completely relies on manual tuning by experienced technologists. With a fast adoption of massive MIMO technology in future 5G wireless systems, demands on microwave filters will be increased in an unprecedented pace. It can be foreseen that a robot automatic tuning (RAT) system with “adaptive thinking” capability will be an inevitable trend in the industry.
In this presentation, a “perception” module for the robot, named Model-based Vector Fitting (MVF) method, will be introduced. The perception module analytically extracts the circuit model of a microwave filtering network at any tuning stage in a RAT process. The method incorporates the merits of conventional Cauchy method and vector fitting (VF) method. The MVF method allows pre-assigning the orders of both system zeros and poles. As the coupling topologies of a filtering network is determined by the number of system zeros, the MVF method does not suffer from the over-fitting and under-fitting problems that other method has to deal with. Having had the system model determined, a transversal coupling matrix can be reconstructed from the measured S-parameters. Consequently, the transversal coupling matrix is transformed to the targeted coupling topology corresponding to the physical layout of the filtering network. The transformation strategies for various filtering networks will also be briefly reviewed. A number of practical examples will be demonstrated, including a high order filter, coaxial diplexer and dual a band filter, showing a great effectiveness of the proposed method. The model-based Vector Fitting method can also be applied to many other engineering problems, in which the orders of system zeros and poles need to be predefined.
Biography:
Ke-Li Wu received the B.S. and M.Eng. from the Nanjing University of Science and Technology, Nanjing, China, in 1982 and 1985, respectively, and the Ph.D. degree from Laval University, Canada, in 1989. From 1989 to 1993, he was with the Communications Research Laboratory, McMaster University. In 1993, he joined the COM DEV International (Now, Honeywell Aerospace), where he was a Principal Member of Technical Staff. Since October 1999, he has been with The Chinese University of Hong Kong, Hong Kong, where he is a Professor and the Director of the Radiaofrequency Radiation Research Laboratory (R3L).
He has authored numerous publications in the areas of EM modeling, microwave passive components, microwave filter and antenna engineering. His current research interests include circuit domain modeling of EM problems, RF and microwave circuits and systems, synthesis theory and robot automatic tuning (RAT) of microwave filters, decoupling techniques for multiple antennas in both wireless terminals and massive MIMO array antennas.
Prof. Wu is a Fellow of IEEE, a member of IEEE MTT-8 subcommittee (Filters and Passive Components) and also serves as a TPC member for many prestigious international conferences including International Microwave Symposium. He was an Associate Editor of IEEE Transactions on MTT from 2006 to 2009. He was the recipient of the 1998 COM DEV Achievement Award for the development of exact EM design software of microwave filters and multiplexers and Asia Pacific Microwave Conference Prize in 2008 and 2012, respectively.