Surface acoustic wave filters with attenuation poles generated by impedance circuits

摘要

The surface acoustic wave filter combines a connected two-port impedance circuit with a two-port surface acoustic wave resonator filter circuit in parallel or in series. The 2-port impedance circuit has an impedance that generates an attenuation pole by making an open circuit impedance of the surface acoustic wave filter equal to the short circuit impedance. High attenuation over a wide range of stopband frequencies is obtained in this way and is combined with steep roll-off between the passband and the stopband.