1. New synthesis of parallel-coupled line bandpass filters with Chebyshev responses
- Author
-
Chin, Kuo-Sheng, Chiou, Yi-Chyun, and Kuo, Jen-Tsai
- Subjects
Electric filters, Bandpass -- Design and construction ,Chebyshev approximation -- Methods ,Microwave communications -- Research ,Bandwidth -- Measurement ,Bandwidth allocation ,Bandwidth technology ,Business ,Computers ,Electronics ,Electronics and electrical industries - Abstract
Parallel-coupled line filters with Chebyshev pass-bands are synthesized based on the insertion-loss functions derived by converting the composite ABCD matrices of all coupled stages. With the synthesis, both the electromagnetic simulation and measurement results have accurate in-band response and bandwidth. Simultaneous equations for Chebyshev filters of order N < 9 are derived for determining geometric parameters of the coupled stages. The tradeoff between circuit bandwidth and ripple level is discussed. In experiments, three planar or quasi-planar structures, including the coupled-line with aperture in the ground plane, the three-line microstrip, and the broadside-coupled lines, are employed to realize the end stages for implementing the high coupling levels. Experimental filters of order up to nine with fractional bandwidth of 30% or 40% are fabricated and measured. The results show good agreement with predictions by the theory and simulation. Index Terms--Bandpass filters, Chebyshev response, insertion-loss function, parallel-coupled line filter, strong coupling.
- Published
- 2008