Exact Design for Equiripple Magnitude and Delay Response of Stub-Loaded Bandpass Filter

Aiming at achieving the equiripple response in both magnitude and group delay, a synthesis design algorithm is presented for a stub-loaded wideband bandpass filter. The filter consists of a pair of coupled lines and two short-circuited stubs. The transfer function is given for obtaining the line impedances when the equiripple conditions are met in both delay and magnitude simultaneously. According to the synthesis procedure, the impedances of each element can be calculated directly for given in-band ripple and fractional bandwidth. In order to verify the algorithm, four filter design sets are given for verification, which prove that the algorithm is effective.