Filters with bulk acoustic wave devices

A band rejection filter with bulk acoustic wave resonators, the band rejection filter comprising:

• a series bulk acoustic wave resonator including a first support layer, a first piezoelectric layer over the first support layer, first and second multi-gradient raised frame structures over the first piezoelectric layer, the first and second multi-gradient raised frame structures located on opposing sides of a first acoustically active region, and a first passivation layer over the first and second multi-gradient raised frame structures, the series bulk acoustic wave resonator having a first resonant frequency and a first anti-resonant frequency;
• and
• a shunt bulk acoustic wave resonator including a second support layer, a second piezoelectric layer over the second support layer, and third and fourth multi-gradient raised frame structures over the second piezoelectric layer, the third and fourth multi-gradient raised frame structures located on opposing sides of a second acoustically active region, and a second passivation layer over the third and fourth multi-gradient raised frame structures, the third and fourth multi-gradient raised frame structures being different than the first and second multi-gradient raised frame structures, the shunt bulk acoustic wave resonator having a second resonant frequency and a second anti-resonant frequency, the third and fourth multi-gradient raised frame structures contribute to the shunt bulk acoustic wave resonator having a higher quality factor below the second resonant frequency than the series bulk acoustic wave resonator has below the first resonant frequency, and the band rejection filter having a rejection band.

A radio frequency module comprising:

• a filter including:
• a shunt bulk acoustic wave resonator including a first support layer, a first piezoelectric layer over the first support layer, and first and second multi-gradient raised frame structures over the first piezoelectric layer, the first and second multi-gradient raised frame structures located on opposing sides of an active region, and a first passivation layer over the first and second multi-gradient raised frame structures, the shunt bulk acoustic wave resonator having a first resonant frequency and a first anti-resonant frequency;
• a series bulk acoustic wave resonator including a second support layer, a second piezoelectric layer over the second support layer, third and fourth multi-gradient raised frame structures over the second piezoelectric layer, and a second passivation layer over the third and fourth multi-gradient raised frame structures, the third and fourth multi-gradient raised frame structures being different than the first and second multi-gradient raised frame structures, the series bulk acoustic wave resonator having a second resonant frequency and a second anti-resonant frequency, the third and fourth multi-gradient raised frame structures contributing to the series bulk acoustic wave resonator having a higher quality factor below the second resonant frequency than the shunt bulk acoustic wave resonator has below the first resonant frequency, and the filter having a pass band;
• and
• a radio frequency circuit element coupled to the filter, the filter and the radio frequency circuit element being enclosed within a common package.