Self-adaptive MEMS loudspeaker driving circuit

Abstract

The invention relates to the technical field of micro electro mechanical systems, in particular to a self-adaptive MEMS (micro electro mechanical system) loudspeaker driving circuit, which comprises an amplification unit, an input end of the amplification unit is connected with an audio input signal, and an output signal of the amplification unit is connected with an MEMS loudspeaker; the input end of the boosting unit is connected with power supply voltage, and the output end of the boosting unit outputs at least one boosting voltage; the MEMS speaker is selectively operable at one of the boost voltages or the supply voltage. The MEMS loudspeaker can selectively work under a boost voltage or a power supply voltage, can adaptively select a working voltage, does not need to work under a high voltage for a long time, and is beneficial to improving the anti-electromagnetic interference capability.

Description

Technical Field

[0001] The present invention relates to the field of micro-electromechanical technology, and in particular to a MEMS speaker driving circuit. Background Art

[0002] MEMS speakers have gradually replaced traditional dynamic or moving iron speakers due to their advantages such as miniaturization, low power consumption and good reliability. However, the circuit characteristics of MEMS speakers in the prior art are characterized by capacitive loads, and the driving voltage requires a high voltage of 15V to 20V. The signal amplitude is large, which will produce high swings, and the circuit has poor anti-electromagnetic interference capabilities. Summary of the invention

[0003] In view of the above problems, an object of the present invention is to provide an adaptive MEMS speaker driving circuit.

[0004] An adaptive MEMS speaker driving circuit, comprising:

[0005] an amplifying unit, wherein an input end of the amplifying unit is connected to an audio input signal, and an output signal of the amplifying unit is connected to a MEMS speaker;

[0006] A boost unit, wherein an input end of the boost unit is connected to a power supply voltage, and an output end of the boost unit outputs at least one boost voltage;

[0007] The MEMS speaker can selectively operate at one of the boost voltages or the power supply voltage.

[0008] The adaptive MEMS speaker driving circuit of the present invention comprises a selection unit, which can selectively output the boost voltage or the power supply voltage under the action of a control signal.

[0009] The adaptive MEMS loudspeaker driving circuit of the present invention comprises an amplitude detection unit, wherein the amplitude detection unit detects the amplitude of the audio input signal, and the output end of the amplitude detection unit outputs the control signal.

[0010] In the adaptive MEMS speaker driving circuit described in the present invention, the amplitude detection unit outputs a first signal when the amplitude of the audio input signal is greater than a reference amplitude, and outputs a second signal when the amplitude of the audio input signal is less than the reference amplitude, and the selection unit outputs a first boosted voltage under the action of the first signal, and outputs the power supply voltage under the action of the second signal.

[0011] In the adaptive MEMS speaker driving circuit of the present invention, the amplitude detection unit outputs a first signal when the amplitude of the audio input signal is greater than a first reference amplitude, outputs a second signal when the amplitude of the audio input signal is greater than the first reference amplitude and less than a second reference amplitude, and outputs a third signal when the amplitude of the audio input signal is greater than the second reference amplitude and less than a third reference amplitude;

[0012] The selection unit outputs a first boosted voltage under the action of the first signal, outputs a second boosted voltage under the action of the second signal, and outputs the power supply voltage under the action of the third signal.

[0013] In the adaptive MEMS speaker driving circuit of the present invention, the first input end of the amplifying unit is connected to the audio input signal via a first capacitor, and the second input end of the amplifying unit is connected to a ground terminal via a second capacitor.

[0014] In the adaptive MEMS speaker driving circuit of the present invention, the first output end of the amplifying unit is connected to the first input end of the MEMS speaker via a third capacitor, and the second output end of the amplifying unit is connected to the second input end of the MEMS speaker via a fourth capacitor.

[0015] In the adaptive MEMS speaker driving circuit of the present invention, the first input terminal of the MEMS speaker is connected to the output terminal of the selection unit through a first resistor, and the second input terminal of the MEMS speaker is connected to the ground terminal through a second resistor.

[0016] In the adaptive MEMS speaker driving circuit of the present invention, the amplification unit is a differential amplifier, and the boost unit is a BOOST power converter or a charge pump.

[0017] In the adaptive MEMS speaker driving circuit of the present invention, the power supply voltage is 3.3V to 4.2V or 1.5V to 3V.

[0018] Beneficial effects: The MEMS speaker of the present invention can selectively operate under a boost voltage or a power supply voltage, can adaptively select the operating voltage, does not need to operate under high voltage for a long time, and is beneficial to improving the anti-electromagnetic interference capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a principle block diagram of an adaptive MEMS speaker driving circuit according to a specific embodiment of the present invention;

[0020] Figure 2 It is a principle block diagram of an adaptive MEMS speaker driving circuit according to another specific embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0023] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0024] Reference Figure 1 , an adaptive MEMS speaker driving circuit, comprising,

[0025] An amplifier unit 1, wherein an input end of the amplifier unit 1 is connected to an audio input signal Audio IN, and an output signal of the amplifier unit 1 is connected to a MEMS speaker 2;

[0026] A boost unit 3, wherein an input end of the boost unit 3 is connected to a power supply voltage VDD, and an output end of the boost unit 3 outputs at least one boost voltage;

[0027] The MEMS speaker 2 can selectively operate at a boosted voltage, such as the first boosted voltage Vout or the power supply voltage VDD.

[0028] The MEMS speaker of the present invention can selectively work under a boost voltage or an input voltage, and can adaptively select the working voltage, and does not need to work under a high voltage for a long time, which is beneficial to improving the anti-electromagnetic interference capability.

[0029] A preferred embodiment of the present invention comprises a selection unit 4, which can selectively output the first boost voltage Vout or the power supply voltage VDD under the action of a control signal. The selection unit 4 can be implemented by a MOS transistor.

[0030] A preferred embodiment of the present invention comprises an amplitude detection unit 5, which detects the amplitude of the audio input signal AudioIN, and an output end of the amplitude detection unit 5 outputs a control signal.

[0031] In a preferred embodiment of the present invention, the amplitude detection unit 5 outputs a first signal when the amplitude of the audio input signal Audio IN is greater than a reference amplitude, and outputs a second signal when the amplitude of the audio input signal Audio IN is less than the reference amplitude. The selection unit 4 outputs a first boosted voltage Vout under the action of the first signal, and outputs a power supply voltage VDD under the action of the second signal.

[0032] The present invention selects whether the MEMS speaker operates at a power supply voltage VDD or a higher first boost voltage Vout based on the amplitude of the audio input signal, thereby optimizing the performance of the MEMS speaker and improving the anti-electromagnetic interference capability.

[0033] A preferred embodiment of the present invention, referring to Figure 2 The amplitude detection unit 5 outputs a first signal when the amplitude of the audio input signal Audio IN is greater than a first reference amplitude, outputs a second signal when the amplitude of the audio input signal Audio IN is greater than the first reference amplitude and less than the second reference amplitude, and outputs a third signal when the amplitude of the audio input signal Audio IN is greater than the second reference amplitude and less than the third reference amplitude; the selection unit 4 outputs a first boosted voltage Vout under the action of the first signal, outputs a second boosted voltage Vout1 under the action of the second signal, and outputs a power supply voltage VDD under the action of the third signal, and the first boosted voltage Vout is greater than the second boosted voltage Vout1 and greater than the power supply voltage VDD.

[0034] By setting a stepped reference amplitude, it is beneficial to adaptively adjust the operating voltage of the MEMS speaker and improve the performance of the MEMS speaker.

[0035] In a preferred embodiment of the present invention, the first input terminal IN+ of the amplifier unit 1 is connected to the audio input signal Audio IN through the first capacitor C1, and the second input terminal IN- of the amplifier unit 1 is connected to the ground through the second capacitor C2.

[0036] In a preferred embodiment of the present invention, the first output terminal OUT- of the amplifying unit 1 is connected to the first input terminal VOUT- of the MEMS speaker 2 through the third capacitor C3, and the second output terminal OUT+ of the amplifying unit 1 is connected to the second input terminal VOUT+ of the MEMS speaker 2 through the fourth capacitor C4.

[0037] In a preferred embodiment of the present invention, the first input terminal VOUT- of the MEMS speaker 2 is connected to the output terminal of the selection unit 4 through the first resistor R1, and the second input terminal VOUT+ of the MEMS speaker 2 is connected to the ground terminal through the second resistor R2.

[0038] In a preferred embodiment of the present invention, the amplifying unit 1 is a differential amplifier, and the boosting unit 3 is a BOOST power converter or a charge pump.

[0039] In a preferred embodiment of the present invention, the power supply voltage VDD is 3.3V to 4.2V or 1.5V to 3V.

[0040] Through the description and drawings, typical embodiments of the specific structures of the specific implementation methods are given, and other transformations can be made based on the spirit of the present invention. Although the above invention proposes the existing preferred embodiments, these contents are not intended to be limiting.

[0041] For those skilled in the art, various changes and modifications will undoubtedly be obvious after reading the above description. Therefore, the attached claims should be regarded as covering all changes and modifications of the true intent and scope of the present invention. Any and all equivalent ranges and contents within the scope of the claims should be considered to still be within the intent and scope of the present invention.

Claims

1. An adaptive MEMS speaker driving circuit, characterized in that: include, an amplifying unit, wherein an input end of the amplifying unit is connected to an audio input signal, and an output signal of the amplifying unit is connected to a MEMS speaker; A boost unit, wherein an input end of the boost unit is connected to a power supply voltage, and an output end of the boost unit outputs at least one boost voltage; The MEMS speaker can selectively operate at one of the boost voltages or the power supply voltage.

2. The adaptive MEMS speaker driving circuit according to claim 1, characterized in that: The device comprises a selection unit, which can selectively output the boost voltage or the power supply voltage under the action of a control signal.

3. The adaptive MEMS speaker driving circuit according to claim 2, characterized in that: It comprises an amplitude detection unit, which detects the amplitude of the audio input signal, and the output end of the amplitude detection unit outputs the control signal.

4. The adaptive MEMS speaker driving circuit according to claim 3, characterized in that: The amplitude detection unit outputs a first signal when the amplitude of the audio input signal is greater than a reference amplitude, and outputs a second signal when the amplitude of the audio input signal is less than the reference amplitude. The selection unit outputs a first boosted voltage under the action of the first signal, and outputs the power supply voltage under the action of the second signal.

5. The adaptive MEMS speaker driving circuit according to claim 3, characterized in that: The amplitude detection unit outputs a first signal when the amplitude of the audio input signal is greater than a first reference amplitude, outputs a second signal when the amplitude of the audio input signal is greater than the first reference amplitude and less than a second reference amplitude, and outputs a third signal when the amplitude of the audio input signal is greater than the second reference amplitude and less than a third reference amplitude; The selection unit outputs a first boosted voltage under the action of the first signal, outputs a second boosted voltage under the action of the second signal, and outputs the power supply voltage under the action of the third signal.

6. The adaptive MEMS speaker driving circuit according to claim 1, characterized in that: The first input end of the amplifying unit is connected to the audio input signal through a first capacitor, and the second input end of the amplifying unit is connected to a ground end through a second capacitor.

7. The adaptive MEMS speaker driving circuit according to claim 1, characterized in that: The first output end of the amplifying unit is connected to the first input end of the MEMS speaker through a third capacitor, and the second output end of the amplifying unit is connected to the second input end of the MEMS speaker through a fourth capacitor.

8. The adaptive MEMS speaker driving circuit according to claim 1, characterized in that: The first input terminal of the MEMS speaker is connected to the output terminal of the selection unit through a first resistor, and the second input terminal of the MEMS speaker is connected to the ground terminal through a second resistor.

9. The adaptive MEMS speaker driving circuit according to claim 1, characterized in that: The amplifying unit is a differential amplifier, and the boosting unit is a BOOST power converter or a charge pump.

10. The adaptive MEMS speaker driving circuit according to claim 1, characterized in that: The power supply voltage is 3.3V to 4.2V or 1.5V to 3V.

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