High CM suppression wideband balanced microstrip BPF using dual‐mode resonator

Abstract

In this letter, a novel high selectivity and common‐mode (CM) suppression wideband balanced microstrip passband filter (BPF) is proposed using the short stub centrally loaded short‐ended resonators (SSCLSR). The odd‐mode resonant frequency of the SSCLSR can be flexibly controlled by the short stub, whereas the even‐mode one is fixed. First, the wideband single‐ended BPF are designed based on the microstrip SSCLSR with the parallel coupled microstrip line input/output (I/O). Two transmission zeros near the passband edges can be generated due to the main path signal counteraction and source‐loaded coupling. Further, the CM equivalent half circuits of the balanced BPF based on the wideband single‐ended BPF are investigated in detail. Thus, a wideband balanced BPF with high CM suppression within the passband is designed, fabricated, and measured. Good agreement between simulated and measured results is obtained. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2940–2944, 2014

High common‐mode rejection balanced bandpass filter using novel coupling scheme and source‐loaded coupling technique

“…Wide bandwidth and wide upper stopband in DM performance with enhanced CM rejection are achieved simultaneously. What's more, the source-loaded coupling (SLC) technique 9,10 and CQ structure 11 are also effective ways to upgrade the performance of balanced BPFs. Multiple TZs can be obtained both in DM and CM responses.…”

“…In recent years, more and more research works about balanced bandpass filters (BPFs) has been conducted, and a series of articles have been published. [1][2][3][4][5][6][7][8][9][10][11][12] Several advanced techniques are proposed to design balanced BPFs. The mixed electromagnetic coupling technology is applied in Xiao et al 1 and Yan et al, 2 where controllable transmission zeros (TZs) in DM are introduced.…”

“…The balanced filters that own both good performance in differential mode (DM) and high common‐mode (CM) rejection are urgently needed in modern communication systems. In recent years, more and more research works about balanced bandpass filters (BPFs) has been conducted, and a series of articles have been published 1–12 . Several advanced techniques are proposed to design balanced BPFs.…”