Microphone circuit, microphone module, and method for raising sound pressure overload point of microphone

Patent metadata

Field	Value
Publication number	US-12452589-B2
Application number	US-202217918898-A
Country	US
Kind code	B2
Filing date	Apr 28, 2022
Priority date	Apr 1, 2022
Publication date	Oct 21, 2025
Grant date	Oct 21, 2025

Abstract

The invention provides a microphone circuit, which includes an amplifier, a bias resistor and a bias network module. The first terminal of bias resistor connects to the preset bias voltage. The second end of the bias resistor connects the output end of the microphone. The bias network module is used to judge level of the voltage value of the signal. If the voltage value of the signal exceeds the preset voltage value of the threshold voltage group range, connect the impeder corresponding to the bias network module to the input end of the microphone circuit. The invention provides a microphone module and a method for raising sound pressure overload point of microphone. Compared with the related art, the technical scheme of the invention improves the sound pressure overload point of microphone and has good electrical performance.

First claim

What is claimed is:

1. A microphone circuit including:
an amplifier for receiving a signal output by an external microphone, and amplifying the signal;
a bias resistor having a first end connecting to a preset bias voltage and a second end connecting to an output end of the microphone and connecting to an input end of the amplifier;
wherein,
the amplifier serves as an input end of the microphone circuit; the output end of the amplifier serves as the output end of the microphone circuit;
the microphone circuit further includes a bias network module connected to the input end of the microphone circuit for judging a voltage value of the signal;
when the voltage value of the signal exceeds a preset voltage value of a threshold voltage group range, connect an impeder corresponding to the bias network module to the input end of the microphone circuit to reduce the vibration amplitude of the signal, the threshold voltage group includes an upper threshold voltage and a lower threshold voltage; the voltage value of the threshold voltage group is less than or equal to that of the upper threshold voltage and greater than or equal to the voltage value of the lower threshold voltage; and
the impeder corresponds to the threshold voltage group one-to-one.

2. The microphone circuit as described in claim 1 , wherein the bias network module includes a first bias network circuit having a first PMOS tube, a first NMOS tube, and a first impeder;
a source electrode of the first PMOS tube connects to the first lower bias voltage, and a drain electrode of the first PMOS tube connects to the drain electrode of the first NMOS tube and a first end of the first impeder;
a grid electrode of the first PMOS tube connects to the input end of the microphone circuit, and the grid electrode of the first PMOS tube is respectively connected to the grid electrode of the first NMOS tube and the second end of the first impeder;
a source electrode of the first NMOS tube connects to the first upper bias voltage; and
the upper threshold voltage of the first bias network circuit is a sum of the voltage value of the first upper bias voltage and the voltage value of the n-type transistor turn-on threshold voltage of the first NMOS tube; the lower threshold voltage of the first bias network circuit is a sum of the voltage value of the first lower bias voltage and the voltage value of the p-type transistor turn-on threshold voltage of the first PMOS tube.

3. The microphone circuit as described in claim 2 , wherein the bias network module further includes an nth bias network circuit, where n is a positive integer and not less than 2; the nth bias network circuit includes a nPMOS tube, a nNMOS tube and a nth impeder;
the source electrode of the nPMOS tube is used for connecting to the nth lower bias voltage, and the drain electrode of the nPMOS tube is respectively connected to the drain electrode of the nNMOS tube and the first end of the nth impeder;
the grid electrode of the nPMOS tube is used for connecting to the input end of the microphone circuit, and the grid electrode of the nPMOS tube is respectively connected to the grid electrode of the nNMOS tube and the second end of the nth impeder;
the source electrode of the nNMOS tube is used to connect to the nth bias voltage;
the upper threshold voltage of the nth bias network circuit is the sum of the voltage value of the nth upper bias voltage and the voltage value of the n-type transistor turn-on threshold voltage of the nNMOS tube; the lower threshold voltage of the nth bias voltage network circuit is the sum of the voltage value of the nth lower bias and the voltage value of the p-type transistor turn-on threshold voltage of the nPMOS tube; and
the first upper bias voltage is smaller than the nth upper bias voltage, and the nth lower bias voltage is smaller than the first lower bias voltage.

4. The microphone circuit as described in claim 1 , wherein the amplifier includes a constant current source and a first transistor;
an input end of the constant current source is connected to the power supply voltage;
an output end of the constant current source is connected to the first source electrode of the transistor, and the first source electrode of the transistor serves as the output end of the microphone circuit;
the first grid electrode of the transistor serves as the input end of the microphone circuit, and the first drain electrode of the transistor is connected to ground.

5. A microphone module, including:
a microphone capacitor and a microphone circuit as described in claim 1 ; wherein
the first end of the microphone capacitor is connected to the bias voltage of microphone, and the second end of the microphone capacitor is connected to the input end of the microphone circuit;
the microphone capacitor is equivalently formed when the microphone is connected to the input end of the microphone circuit.

6. A method for raising a sound pressure overload point of a microphone, which is applied to a microphone circuit having:
an amplifier for receiving a signal output by an external microphone, and amplifying the signal;
a bias resistor having a first end connecting to a preset bias voltage and a second end connecting to an output end of the microphone and connecting to an input end of the amplifier;
wherein,
the amplifier serves as an input end of the microphone circuit; the output end of the amplifier serves as the output end of the microphone circuit;
the microphone circuit further includes a bias network module connected to the input end of the microphone circuit for judging a voltage value of the signal;
and wherein the method includes the following steps of:
receiving the signal;
determining whether a voltage value of the signal exceeds a preset voltage value of a threshold voltage group range: if yes, connecting the preset impeder to the input end of the microphone circuit to reduce the vibration amplitude of the signal, the threshold voltage group includes an upper threshold voltage and a lower threshold voltage; the voltage value of the threshold voltage group is less than or equal to that of the upper threshold voltage and greater than or equal to the voltage value of the lower threshold voltage; if not, sending the received signal to the input end of the amplifier;
the impeder corresponds to the threshold voltage group one-to-one.

7. The method for raising the sound pressure overload point of the microphone as described in claim 6 , wherein, the threshold voltage group includes n pieces of threshold voltage group, and n pieces of impeder; each of the threshold voltage groups corresponds to one of the impeders.

Assignees

• Aac Acoustic Tech Shenzhen Co Ltd

Inventors

• Han Dong
• Kee Chuationg

Classifications

• H04R1/00

  Details of transducers, {loudspeakers or microphones} · CPC title

• H04R3/00 Primary

  Circuits for transducers (arrangements for producing a reverberation or echo sound G10K15/08; amplifiers H03F) · CPC title

• H04R19/005

  using semiconductor materials · CPC title

• H04R3/04

  for correcting frequency response · CPC title

• H04R19/04 Primary

  Microphones (H04R19/01 takes precedence) · CPC title