Automated synthesis of planar wideband bandpass filters based on stepped impedance resonators (SIRs) and shunt stubs through aggressive space mapping (ASM)

This paper is focused on the automated synthesis of wideband bandpass filters by means of aggressive space mapping (ASM). The considered filters are microstrip filters implemented through a combination of shunt connected stepped impedance resonators (SIRs) and grounded stubs coupled through impedance inverters. By virtue of the transmission zeros introduced by the shunt connected SIRs, the filters exhibit a wide rejection band with strong attenuation. The main contribution and originality of the paper is the fact that the layout of the whole filter is automatically generated from the circuit schematic without human intervention in the process. In a first step, the ASM algorithm is applied to the SIR/stub resonators and inverters. After that, each filter cell is automatically generated, and no further optimization is required. As an example, the synthesis of an order-7 bandpass filter is reported. The agreement between the electromagnetic response of the synthesized filter and the target response is very good, pointing out the validity of the proposed synthesis approach.