Double backplate MEMS microphone with a single-ended amplifier input port
View Patent ↗A double backplate microphone having a good signal-to-noise ratio and being produceable at reduced manufacturing costs is provided. A microphone comprises a first backplate BP 1 , a second backplate BP 2 and a membrane M. The microphone further comprises an amplifier AMP with a single-ended input port. The first backplate BP 1 is electrically connected to the single-ended input port.
1. A double backplate microphone, comprising
a micro-electro-mechanical system (MEMS) chip,
an amplifier with an single-ended input port,
a first backplate, electrically connected to the single-ended input port,
a second backplate electrically connected to ground,
a membrane, arranged between the first and the second backplate,
a first resistive element having a resistance >=1 GΩ and electrically connected to the first backplate,
a second resistive element having a resistance >=1 GΩ and electrically connected to the membrane,
a first capacitance C 1 between the first backplate and the membrane,
a second capacitance C 2 between the second backplate and the membrane,
a parasitic capacitance Cp 1 between the first backplate and ground,
a parasitic capacitance Cm between the membrane and ground,
a parasitic capacitance CP 2 between the second backplate and ground, where
4 pF<=Cm=C 1 =C 2 <=8 pF,
Cp 1 =0.1*C 1 ,
Cp 2 =0.5*C 1 ,
the first backplate, the membrane, and the second backplate are arranged on the MEMS-chip.
2. The double backplate microphone of claim 1 , where
the first backplate is biased with a voltage between −2 V and +2 V.
3. The double backplate microphone of claim 1 , where
the membrane is biased with a voltage V 1 relative to the first backplate,
the membrane is biased with a voltage V 2 relative to the second backplate, and
5 V<=V 1 =V 2 <=15 V.
4. The double backplate microphone of claim 1 , where the amplifier is a low noise amplifier.
5. The double backplate microphone of claim 1 , further comprising a carrier substrate and a IC-chip, where
the amplifier comprises amplifier circuits arranged in the IC-chip,
the MEMS-Chip and the IC-chip are arranged on the carrier substrate.
6. The double backplate microphone of claim 1 , further comprising a MEMS-chip, where
the first backplate, the membrane, and the second backplate are arranged on the MEMS-chip,
the amplifier comprises amplifier circuits arranged in the MEMS-chip.
7. The double backplate microphone of claim 1 , where the first resistive element and the second resistive element are realized as surface-mounted device (SMD) components.
8. The double backplate microphone of claim 1 , where the first resistive element and the second resistive element are realized in an IC chip.