Asymmetric parallel-coupled CPW stages for harmonic suppressed (lambda)/4 bandpass filters

A four-pole (lambda)/4 coplanar waveguide (CPW) bandpass filter, terminated with two asymmetric parallel-coupled stages, is proposed. By separately allocating the two unequal transmission zeros, the spurious response at the triplicate passband frequency (3f/sub 0/) is suppressed. Simulated and measured results confirm the attractive features of this proposed filter, i.e. wide passband and good harmonic suppression.