A Compact High-Selective Microstrip Bandpass Filter Used in Up-Converter Modules

In this paper, basic theories and design method about cross-coupled quadruplet microstrip band-pass filter (BPF) were introduced, which has high-selective property by generating a pair of transmission zeros (TZs) in finite frequencies. A design example according to such theories was presented, which has been used in an up-converter module, and satisfies high frequency selective and spurious suppression desires