Band-pass acoustic filter and acoustic sensing apparatus

1. A band-pass acoustic filter, including:

at least two Microelectromechanical Systems, MEMS, microphone chips, which have different resonance bandwidths; and

an Application-Specific Integrated Circuit, ASIC, chip,

wherein the output signals of the MEMS microphone chips are coupled to form and increase one resonance band pass of the band-pass acoustic filter by combining the different resonance bandwidths of the MEMS microphone chips and then are processed in the ASIC chip,

wherein the band-pass acoustic filter further includes a metal case, for forming a back cavity for the MEMS microphone chips, wherein the MEMS microphone chips are acoustically coupled through the back cavity.

2. The band-pass acoustic filter according to claim 1 , wherein each of the MEMS microphone chips is mounted above the acoustic port of a substrate.

3. The band-pass acoustic filter according to claim 1 , further including a substrate, wherein the metal case and the substrate form an enclosed back cavity together.

4. The band-pass acoustic filter according to claim 1 , wherein the output signals are coupled in series.

5. The band-pass acoustic filter according to claim 1 , wherein the resonance frequency of each of the MEMS microphone chips is adjusted by setting at least one of diaphragm resonance frequency, front-chamber size and acoustic port dimension of the MEMS microphone chip.

6. An acoustic sensing apparatus, comprising the band-pass acoustic filter according to claim 1 , for sensing a sound wave.

7. The acoustic sensing apparatus according to claim 6 , wherein the sound wave includes ultrasonic wave.

8. The acoustic sensing apparatus according to claim 6 , wherein the acoustic sensing apparatus is a microphone.