Filter, radio frequency device and electronic apparatus

A filter, comprising:

• a series branch, comprising M series resonators arranged in series;
• N parallel branches, each of the N parallel branches comprising a parallel resonator;
• and
• a bridged branch, comprising a bridged resonator and a first inductor,
• wherein each of the parallel branches comprises a first end and a second end that are opposite to each other, the first end of each of the parallel branches is grounded, the second end of each of the parallel branches is connected with the series branch,
• the bridged branch comprises a third end and a fourth end, the third end is located at a side of the bridged resonator away from the first inductor, the fourth end is located at a side of the first inductor away from the bridged resonator, the third end is connected to the first end of the ith parallel branch, the fourth end is connected to the second end of the (i+k)th parallel branch, both M and N are positive integers greater than or equal to 3, i is a positive integer greater than or equal to 1 and less than or equal to N−k, and k is a positive integer greater than or equal to 2,
• wherein the series branch comprises an input end and an output end that are arranged opposite to each other, the M series resonators are arranged between the input end and the output end, the filter further comprises:
• a second inductor, wherein the second inductor is arranged in parallel with the first series resonator.

A filter, comprising:

• a series branch, comprising M series resonators arranged in series;
• N parallel branches, each of the N parallel branches comprising a parallel resonator;
• and
• a bridged branch, comprising a bridged resonator and a first inductor,
• wherein each of the parallel branches comprises a first end and a second end that are opposite to each other, the first end of each of the parallel branches is grounded, the second end of each of the parallel branches is connected with the series branch,
• the bridged branch comprises a third end and a fourth end, the third end is located at a side of the bridged resonator away from the first inductor, the fourth end is located at a side of the first inductor away from the bridged resonator, the third end is connected to the first end of the ith parallel branch, the fourth end is connected to the second end of the (i+k)th parallel branch, both M and N are positive integers greater than or equal to 3, i is a positive integer greater than or equal to 1 and less than or equal to N−k, and k is a positive integer greater than or equal to 2,
• wherein the bulk acoustic wave resonator comprises:
• a substrate;
• a piezoelectric film;
• a first driving electrode;
• and
• a second driving electrode.