Tunable acoustic wave filter switchable between band pass and band reject characteristics

摘要

A tunable acoustic wave filter is switchable between band-pass and band reject characteristic.The filter comprises in a T-ype arrangement a first and second series resonator (82A...82N, 83A...83N), each with a switch in parallel (182A...182N, 183A...183N), and a third resonator (84A...84N) to ground. The first and second series resonators have differing resonance and anti-resonance frequencies. Depending on the position of the two switches the filter can operate with band-pass or band reject characteristic. Each resonator may have variable capacitors in parallel and in series to allow for tunability of the filter characteristic.