Audio signal limiting circuit

Abstract

The utility model discloses provide an audio signal limiting circuit, include: at least one way limiting branch, any limiting branch includes: gain module is used for receiving audio signal, and carries out amplification processing to audio signal, generates audio amplification signal and exports, conversion module is used for converting the voltage type of audio amplification signal, obtains audio conversion signal, comparison module is used for according to the size between the voltage of audio conversion signal and threshold voltage, and output comparison signal, and comparison signal has first state and second state, limiting module is coupled with comparison module and gain module respectively, when comparison signal has first state, is in the gating state, and the passage between gain module and limiting module is gated to access limiting resistance, and when comparison signal has second state, is in the off state, and the passage between gain module and limiting module is disconnected to disconnect limiting resistance. Adopt above -mentioned technical scheme, can effectively limit the amplitude of audio amplification signal.

Description

Technical Field

[0001] This utility model relates to the field of circuit technology, and in particular to an audio signal limiting circuit. Background Technology

[0002] Audio power amplifiers are mainly used to amplify input audio signals and then use the amplified audio signals to drive passive acoustic components (such as speakers, headphones, etc.) to produce sound.

[0003] In practical applications, to prevent excessively loud audio signals from damaging connected equipment, a limiting circuit is typically included in the audio power amplifier circuit to prevent audio signal distortion or cancellation (wave suppression), thereby controlling the amplitude of the amplified audio signal. The limiting circuit can be configured with a threshold value; exceeding this threshold automatically attenuates the audio signal, helping to prevent excessively loud audio signals that could distort the output signal or damage the equipment. However, existing limiting schemes still exhibit issues with excessively large audio signal amplitudes. Utility Model Content

[0004] In view of this, the present invention provides an audio signal limiting circuit that can effectively limit the amplitude of the amplified audio signal and improve the service life of the equipment using the audio signal limiting circuit.

[0005] This utility model provides an audio signal limiting circuit, comprising: at least one limiting branch, wherein any limiting branch includes:

[0006] A gain module is used to receive an audio signal, amplify the audio signal, generate an amplified audio signal, and output the amplified audio signal, wherein the amplified audio signal has a voltage of the first type.

[0007] A conversion module, coupled to the output of the gain module, is used to convert the voltage type of the audio amplified signal to obtain an audio converted signal, which has a second type of voltage.

[0008] A comparison module, coupled to the conversion module, is used to output a comparison signal based on the magnitude between the voltage of the audio conversion signal and a threshold voltage, the comparison signal having a first state and a second state;

[0009] The limiting module is coupled to both the comparison module and the gain module. When the comparison signal has the first state, it is in a strobe state, strobes the path between the gain module and the limiting module to connect the limiting resistor; and when the comparison signal has the second state, it is in a disconnect state, disconnects the path between the gain module and the limiting module to disconnect the limiting resistor.

[0010] Optionally, the limiting module includes: a switching unit and a limiting unit, wherein the limiting unit has the limiting resistor, wherein:

[0011] A switching unit is coupled to both the comparison module and the limiting unit. The limiting unit is coupled to the input terminal of the gain module. When the comparison signal has the first state, the switching unit is in a selected state, and the limiting unit is turned on via an optocoupler, connecting the limiting resistor to the input terminal of the gain module in parallel. When the comparison signal has the second state, the switching unit is in an open state, and the limiting unit is turned off via an optocoupler, disconnecting the limiting resistor from the input terminal of the gain module.

[0012] Optionally, the limiting module satisfies at least one or more of the following:

[0013] The switching unit includes: a transistor, the control terminal of which is coupled to the comparison module, the first terminal of which is coupled to the limiting unit, and the second terminal of which is grounded;

[0014] The limiting unit includes an optocoupler and a first limiting resistor. The optocoupler includes a light-emitting diode (LED) and a second limiting resistor. The first end of the LED is coupled to the switching unit, and the second end of the LED is coupled to the first end of the first limiting resistor. The second limiting resistor is coupled to the input terminal of the gain module in parallel. The second end of the first limiting resistor is coupled to the gain module.

[0015] Optionally, the comparison module includes: a comparison unit and a driving unit, wherein:

[0016] The comparison unit is coupled to the driving unit and the conversion module respectively, and is used to generate an initial comparison signal with a first state when the voltage of the audio conversion signal is greater than the threshold voltage, and to generate an initial comparison signal with a second state when the voltage of the audio conversion signal is less than the threshold voltage.

[0017] The driving unit is coupled to the limiting module and is used to perform voltage division driving on the initial comparison signal to obtain the comparison signal.

[0018] Optionally, the comparison module satisfies at least one or more of the following:

[0019] The comparison unit includes a first operational amplifier, a first input terminal of the first operational amplifier is adapted to input the audio conversion signal, a second input terminal of the first operational amplifier is adapted to input the threshold voltage, and an output terminal of the first operational amplifier outputs the initial comparison signal.

[0020] The driving unit includes a driving diode, a first driving resistor, and a second driving resistor, wherein: the first end of the driving diode is coupled to the comparator unit, and the second end of the driving diode is coupled to the first end of the first driving resistor and the first end of the second driving resistor, respectively; the second end of the first driving resistor is grounded; and the second end of the second driving resistor is coupled to the limiting module.

[0021] Optionally, the audio signal limiting circuit further includes:

[0022] A voltage supply module, coupled to the comparison module, is used to provide the threshold voltage, and the amplitude of the threshold voltage is variable;

[0023] The feedback module is coupled to the comparison module and the limiting module respectively, and is used to provide the cutoff frequency;

[0024] The voltage supply module includes: a voltage source, coupled to the voltage source, and a first voltage divider unit consisting of a first voltage supply resistor, a second voltage supply resistor, and a third voltage supply resistor, wherein: a first terminal of the first voltage supply resistor is coupled to the voltage source, a second terminal of the first voltage supply resistor is coupled to the first terminal of the second voltage supply resistor, and a third terminal of the first voltage supply resistor is grounded through the third voltage supply resistor; a second terminal of the second voltage supply resistor is coupled to the comparison module; wherein the resistance value of the first voltage supply resistor is variable;

[0025] The feedback module includes a feedback capacitor, a first feedback resistor, and a second feedback resistor, wherein: the first end of the feedback capacitor is coupled to the comparison module; the second end of the feedback capacitor is coupled to the limiting module and the first end of the second feedback resistor through the first feedback resistor; and the second end of the second feedback resistor is grounded. The feedback capacitor and the first feedback resistor provide the cutoff frequency.

[0026] Optionally, the conversion module includes: a conversion unit and a compensation unit, wherein:

[0027] The conversion unit is coupled to the gain module and the compensation unit respectively, and is used to be in the on state when the audio amplification signal is in the positive half-cycle to convert the type of the audio amplification signal to obtain an audio conversion signal with a second type of voltage; and to be in the off state when the audio amplification signal is in the negative half-cycle to shut off the path between the audio amplification signal and the comparison module.

[0028] The compensation unit is coupled to the comparison module and is used to compensate the audio conversion signal when the conversion unit is in the on state.

[0029] Optionally, the conversion module satisfies at least one or more of the following:

[0030] The conversion unit includes a second operational amplifier, a first rectifier diode, and a second rectifier diode, wherein: the first terminal of the second operational amplifier is coupled to the compensation unit and the first terminal of the first rectifier diode, respectively; the second terminal of the second operational amplifier is grounded; the third terminal of the second operational amplifier is coupled to the second terminal of the first rectifier diode and the first terminal of the second rectifier diode, respectively; and the second terminal of the second rectifier diode is coupled to the compensation unit.

[0031] The compensation unit includes a first compensation resistor, a second compensation resistor, and a third compensation resistor, wherein: a first end of the first compensation resistor is coupled to the gain module; a second end of the first compensation resistor is coupled to a first end of the second compensation resistor and the conversion unit; a second end of the second compensation resistor is coupled to a first end of the third compensation resistor and the conversion unit; and a second end of the third compensation resistor is coupled to the comparison module.

[0032] Optionally, the gain module includes: a second voltage divider unit and a gain unit, wherein:

[0033] The second voltage divider unit is coupled to the gain unit and the limiting module respectively, and is adapted to perform voltage division processing on the audio signal according to the voltage division ratio of the second voltage divider unit and the limiting resistor to which the limiting module is connected, to obtain an audio voltage-divided signal;

[0034] The gain unit is coupled to the limiting module and the conversion module respectively, and is used to amplify the audio voltage divider signal to generate the amplified audio signal.

[0035] Optionally, the gain module satisfies at least one or more of the following:

[0036] The second voltage divider unit includes: a first voltage divider resistor and a second voltage divider resistor, wherein a first terminal of the first voltage divider resistor is adapted to input the audio signal, and a second terminal of the first voltage divider resistor is coupled to the first terminal of the second voltage divider resistor and the limiting module; the second terminal of the second voltage divider resistor is coupled to the limiting module and grounded;

[0037] The gain unit includes a third operational amplifier, a first gain resistor, and a second gain resistor. The first input terminal of the third operational amplifier is coupled to the second voltage divider unit and the limiting module, respectively. The second input terminal of the third operational amplifier is coupled to the first terminal of the first gain resistor and the first terminal of the second gain resistor, respectively. The second terminal of the first gain resistor is grounded. The second terminal of the second gain resistor is coupled to the output terminal of the third operational amplifier.

[0038] Compared with the prior art, the technical solution of this utility model embodiment has the following advantages:

[0039] The audio signal limiting circuit provided in this embodiment of the invention has a conversion module that can convert the voltage type of the audio amplified signal, so that the audio converted signal has a second type of voltage. The comparison module can then output a comparison signal based on the difference between the voltage of the audio converted signal and a threshold voltage, such that the first and second states of the comparison signal are correlated with the amplitude of the audio amplified signal. When the comparison signal is in the first state, the limiting module is in a selected state, thereby selecting the path between the gain module and the limiting module to connect the limiting resistor, thus reducing the voltage amplitude at the input of the gain module. When the comparison signal is in the second state, it is in an open state, disconnecting the path between the gain module and the limiting module, thus disconnecting the limiting resistor, thereby increasing the voltage amplitude at the input of the gain module. This achieves dynamic adjustment of the audio amplified signal, ensuring that the amplitude of the audio amplified signal is always within a preset threshold, effectively limiting the amplitude of the audio amplified signal and extending the service life of devices using this audio signal limiting circuit. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0041] Figure 1 This diagram shows a schematic of an audio signal limiting circuit according to an embodiment of the present invention.

[0042] Figure 2 This diagram illustrates the specific structure of an audio signal limiting circuit according to the first embodiment of the present invention.

[0043] Figure 3 A schematic diagram of the specific structure of an audio signal limiting circuit according to the second embodiment of this utility model is shown. Detailed Implementation

[0044] As described in the background section, in existing limiting schemes, the audio amplification signal still exhibits a large amplitude.

[0045] To address the aforementioned technical problems, this utility model provides an audio signal limiting circuit. The conversion module can convert the voltage type of the audio amplified signal, resulting in a second type of voltage in the converted audio signal. The comparison module can then output a comparison signal based on the difference between the converted audio signal voltage and a threshold voltage. The first and second states of the comparison signal are correlated with the amplitude of the audio amplified signal. When the comparison signal is in the first state, the limiting module is in a selected state, allowing the path between the gain module and the limiting module to be opened, thus connecting a limiting resistor and reducing the voltage amplitude at the input of the gain module. When the comparison signal is in the second state, it is in an open state, disconnecting the path between the gain module and the limiting module, thus disconnecting the limiting resistor and increasing the voltage amplitude at the input of the gain module. This achieves dynamic adjustment of the audio amplified signal, ensuring that the amplitude of the audio amplified signal is always within a preset threshold. Therefore, it effectively limits the amplitude of the audio amplified signal and extends the lifespan of devices using this audio signal limiting circuit.

[0046] In other words, by using the audio signal limiting circuit in this embodiment of the present invention, it is possible to ensure that the audio signal is kept within a safe and acceptable audio level.

[0047] To enable those skilled in the art to better understand and implement this disclosure, the following detailed description of the specific solutions, principles, advantages, and effects of this disclosure is provided with reference to the accompanying drawings and specific embodiments.

[0048] See Figure 1 The diagram shown is a structural schematic of an audio signal limiting circuit according to an embodiment of the present invention. Figure 1 As shown, an audio signal limiting circuit may include at least one limiting branch, wherein, Figure 1 The first limiting branch 100 is shown.

[0049] It should be noted that when the audio signal limiting circuit has multiple limiting branches, the structure of each limiting branch is the same. For example, any limiting branch may include: an input module, an amplification module, a frequency compensation module, and an output module.

[0050] For ease of understanding and explanation, the working principle of the audio signal limiting circuit in this utility model is illustrated by taking the first limiting branch 100 as an example.

[0051] like Figure 1 As shown, the first limiting branch 100 may include: a gain module 110, a conversion module 120, a comparison module 130, and a limiting module 140, wherein:

[0052] Gain module 110 is used to receive audio signal IN, amplify the audio signal IN, generate an amplified audio signal and output it, the amplified audio signal having a first type of voltage;

[0053] The conversion module 120 is coupled to the output terminal of the gain module 110 and is used to convert the voltage type of the audio amplification signal to obtain an audio conversion signal, wherein the audio conversion signal has a second type of voltage.

[0054] The comparison module 130, coupled to the conversion module 120, is used to output a comparison signal based on the magnitude between the voltage of the audio conversion signal and the threshold voltage, the comparison signal having a first state and a second state;

[0055] The limiting module 140 is coupled to the comparison module 130 and the gain module respectively. When the comparison signal has the first state, it is in a strobe state, strobes the path between the gain module 110 and the limiting module 140 to connect the limiting resistor; and when the comparison signal has the second state, it is in a disconnect state, disconnects the path between the gain module 110 and the limiting module 140 to disconnect the limiting resistor.

[0056] Combination Figure 1 Briefly explain the working principle of the audio signal limiting circuit in the embodiments of this utility model:

[0057] When the gain module 110 receives the audio signal IN, it can amplify the audio signal IN to obtain an amplified audio signal and output it to the next stage circuit. It can also provide a matching resistor, which can improve the transmission efficiency and play a current limiting protection role, thereby improving the protection of the subsequent circuit structure.

[0058] At the same time, the conversion module 120 can convert the voltage type of the audio amplified signal so that the audio converted signal has a second type of voltage. Thus, the comparison module 130 can output a comparison signal according to the magnitude between the voltage of the audio converted signal and the threshold voltage, so that the comparison signal has a first state and a second state, and the first state and the second state are related to the amplitude of the audio amplified signal.

[0059] When the comparison signal has a first state, the limiting module 140 is in a selected state, thereby enabling the path between the gain module 110 and the limiting module 140 to connect the limiting resistor, thereby reducing the voltage amplitude at the input terminal of the gain module; and when the comparison signal has a second state, it is in an open state, disconnecting the path between the gain module 110 and the limiting module 140 to disconnect the limiting resistor, thereby reducing the voltage amplitude at the input terminal of the gain module, realizing dynamic adjustment of the audio amplified signal, so that the amplitude of the audio amplified signal is always at a preset threshold, thus effectively limiting the amplitude of the audio amplified signal and improving the service life of the equipment using this audio signal limiting circuit.

[0060] It should be noted that: First, when the audio signal is acquired, the audio signal itself has a voltage value. The "amplification" mentioned in this solution refers to amplifying the voltage value of the audio signal. This solution uses "audio amplified signal" for equivalence explanation. Second, the voltage value corresponding to the audio signal is AC voltage, that is, the first type is AC and the second type is DC. Third, for the description of other limiting branches, please refer to the description of the first limiting branch 100. Fourth, the next stage circuit can refer to an operational amplifier or a speaker device.

[0061] Combination Figure 1 See Figure 2 The diagram shown is a schematic representation of the specific structure of an audio signal limiting circuit according to an embodiment of the present invention. Figure 2 It can be seen that the gain module 110 may include: a second voltage divider unit 112 and a gain unit 114, wherein:

[0062] The second voltage divider unit 112 is coupled to the gain unit 114 and the limiting module 140 respectively, and is adapted to perform voltage division processing on the audio signal IN according to the voltage division ratio of the second voltage divider unit 112 and the limiting resistor to which the limiting module 140 is connected, to obtain an audio voltage divided signal;

[0063] The gain unit 114 is coupled to the limiting module 140 and the conversion module 120 respectively, and is used to amplify the audio voltage divider signal to generate the audio amplified signal.

[0064] Specifically, the second voltage divider unit 112 has a preset voltage division ratio. When the limiting module 140 is connected, it changes the input resistance of one of the input terminals of the gain unit 114, thereby changing the actual voltage division ratio of the second voltage divider unit 112. This allows for dynamic adjustment of the audio voltage division signal input to the gain unit 114. The gain of the gain unit 114 is generally a fixed value, which allows for changing the amplitude of the audio amplified signal.

[0065] In other words, the connection of the limiting resistor is determined based on the audio amplification signal and also acts on the audio amplification signal in return, thus ensuring that the audio signal is kept within a safe and acceptable audio level.

[0066] In this embodiment, the second voltage divider unit 112 may include: a first voltage divider resistor R1 and a second voltage divider resistor R2, wherein the first end of the first voltage divider resistor R1 is adapted to input the audio signal IN, the second end of the first voltage divider resistor R1 is coupled to the first end of the second voltage divider resistor R2 and the limiting module 140 respectively; the second end of the second voltage divider resistor R2 is coupled to the limiting module 140 and grounded.

[0067] Specifically, the first voltage divider resistor R1 and the second voltage divider resistor R2 determine the initial voltage division ratio of the second voltage divider unit 112. By connecting or disconnecting the limiting resistor, the equivalent resistance can be changed, thereby effectively changing the amplitude of the audio amplified signal.

[0068] Furthermore, the first voltage divider resistor R1 and the second voltage divider resistor R2 can also play an impedance transformation role, reducing interference to the audio signal IN, and also play an attenuation role, reducing the problem of damage to the gain unit 114 caused by a sudden increase in the voltage of the audio signal IN.

[0069] In this embodiment, the gain unit 114 may include: a third operational amplifier OA1, a first gain resistor R3, and a second gain resistor R4, wherein the first input terminal of the third operational amplifier OA1 (e.g., the non-inverting input terminal) is coupled to the second voltage divider unit 112 and the limiting module 140 respectively; the second input terminal of the third operational amplifier OA1 is coupled to the first terminal of the first gain resistor R3 and the first terminal of the second gain resistor R4 respectively; the second terminal of the first gain resistor R3 is grounded; and the second terminal of the second gain resistor R4 is coupled to the output terminal of the third operational amplifier OA1.

[0070] Specifically, the third operational amplifier OA1 can amplify the audio signal based on the audio signal at the first input terminal and the feedback amplification effect of the first gain resistor R3 and the second gain resistor R4 to generate an amplified audio signal, which is then output through the output terminal (e.g., port 1 shown in the figure).

[0071] Based on the "virtual short" theory of the third operational amplifier OA1, the voltages at the first and second input terminals of OA1 are the same. The voltage at the first input terminal of OA1 is the voltage divided by the second voltage divider resistor R2, or the equivalent voltage across the second voltage divider resistor R2 and the limiting resistor. Therefore, the voltage drop across the first gain resistor R3 is equal to the voltage at the first input terminal of OA1. Due to the voltage division effect of the first gain resistor R3 and the second gain resistor R4, the voltage of the audio output signal is the total voltage across the first and second gain resistors R3 and R4.

[0072] It should be noted that this utility model does not limit the specific model of the third operational amplifier OA1.

[0073] In this embodiment, see next. Figure 2 The third operational amplifier OA1 may further include: a third input terminal for inputting a first voltage (not shown in the figure); and a fourth input terminal for inputting a second voltage.

[0074] In this embodiment, the first voltage and the second voltage have the same amplitude but opposite signs.

[0075] As an alternative example, the first voltage could be +8VA, while the second voltage could be -8VA.

[0076] See next Figure 2 The conversion module 120 may include: a conversion unit 122 and a compensation unit 124, wherein:

[0077] The conversion unit 122 is coupled to the gain module 110 and the compensation unit 124 respectively, and is used to be in the on state when the audio amplification signal is in the positive half-cycle to convert the type of the audio amplification signal to obtain an audio conversion signal with a second type of voltage; and to be in the off state when the audio amplification signal is in the negative half-cycle to shut off the path between the audio amplification signal and the comparison module.

[0078] The compensation unit 124 is coupled to the comparison module and is used to compensate the audio conversion signal when the conversion unit 122 is in the on state.

[0079] Specifically, in this scheme, the audio signal is an AC voltage with a positive half-cycle and a negative half-cycle. When the audio amplification signal is in the positive half-cycle, the conversion unit 122 is turned on, which can convert the type of the audio amplification signal to obtain an audio conversion signal with a second type of voltage, and the compensation unit 124 can play a compensation role. When the audio amplification signal is in the negative half-cycle, the conversion unit 122 is turned off to cut off the path between the audio amplification signal and the comparison module 130.

[0080] In this embodiment, the conversion unit 122 may include a second operational amplifier OA2, a first rectifier diode D1, and a second rectifier diode D2, wherein: the first terminal (e.g., the inverting input terminal) of the second operational amplifier OA2 is coupled to the compensation unit 124 and the first terminal of the first rectifier diode D1, the second terminal (e.g., the non-inverting input terminal) of the second operational amplifier OA2 is grounded, the third terminal of the second operational amplifier OA2 is coupled to the second terminal of the first rectifier diode D1 and the first terminal of the second rectifier diode D2, and the second terminal of the second rectifier diode D2 is coupled to the compensation unit 124.

[0081] Specifically, when the audio amplification signal is in the positive half-cycle, the voltage at the first terminal of the second operational amplifier OA2 tends to become positive. The second operational amplifier OA2, through a virtual short, makes the voltage at its first and second terminals the same, and approximately 0V. At this time, in order to maintain the voltage at the first terminal of the second operational amplifier OA2, OA2 must output a sufficiently negative voltage to select the first rectifier diode D1 and the second rectifier diode D2, thus performing the conversion operation.

[0082] When the audio amplification signal is in the positive half-cycle, the voltage at the first terminal of the second operational amplifier OA2 tends to 0V. In order to "pull up" the voltage at the first terminal back to 0V, the second operational amplifier OA2 attempts to output a positive voltage, causing the first rectifier diode D1 and the second rectifier diode D2 to be reverse biased and cut off, thus disconnecting the conversion circuit.

[0083] The compensation unit 124 may include a first compensation resistor R5, a second compensation resistor R6, and a third compensation resistor R7, wherein: the first end of the first compensation resistor R5 is coupled to the gain module 110; the second end of the first compensation resistor R5 is coupled to the first end of the second compensation resistor R6 and the conversion unit 122; the second end of the second compensation resistor R6 is coupled to the first end of the third compensation resistor R7 and the conversion unit 122; and the second end of the third compensation resistor R7 is coupled to the comparison module 130. Specifically, the first compensation resistor R5, the second compensation resistor R6, and the third compensation resistor R7 work together to provide compensation, and when the conversion unit 122 is in the on state, different gains can be achieved by adjusting the resistance values ​​of the first compensation resistor R5 and the second compensation resistor R6, that is, audio conversion signals with different amplitudes can be output to the comparison module 130.

[0084] In this embodiment, the comparison module 130 may include: a comparison unit 132 and a driving unit 134, wherein:

[0085] The comparison unit 132 is coupled to the driving unit 134 and the conversion module 120 respectively, and is used to generate an initial comparison signal with a first state when the voltage of the audio conversion signal is greater than the threshold voltage, and to generate an initial comparison signal with a second state when the voltage of the audio conversion signal is less than the threshold voltage.

[0086] The driving unit 134 is coupled to the limiting module 140 and is used to perform voltage division driving on the initial comparison signal to obtain the comparison signal.

[0087] Specifically, the audio conversion signal reflects the amplitude of the audio amplified signal, while the threshold voltage limits the maximum amplitude of the audio amplified signal. By comparing the voltage of the audio conversion signal with the threshold voltage, it can be determined whether the amplitude of the audio amplified signal meets the requirements.

[0088] Specifically, when the voltage of the audio conversion signal is greater than the threshold voltage, it indicates that the amplitude of the audio amplification signal exceeds the set requirements. At this time, an initial comparison signal with a first state can be output so that the limiting module 140 is in the selected state. When the voltage of the audio conversion signal is less than the threshold voltage, it indicates that the amplitude of the audio amplification signal meets the set requirements. At this time, an initial comparison signal with a second state can be output to disconnect the limiting module 140.

[0089] When the output of the comparison unit 132 outputs the initial comparison signal, the drive unit 134 can perform a voltage divider drive operation to output the comparison signal to the limiting module 140.

[0090] In this embodiment, the comparison unit 132 may include a first operational amplifier OA1, the first input terminal (e.g., non-inverting input terminal) of the first operational amplifier OA1 is adapted to input the audio conversion signal, the second input terminal (e.g., inverting input terminal) of the first operational amplifier OA1 is adapted to input the threshold voltage Vth, and the output terminal of the first operational amplifier OA1 outputs the initial comparison signal.

[0091] In other words, this scheme uses the first operational amplifier OA1 to compare the voltage of the audio conversion signal with the threshold voltage.

[0092] The driving unit 134 may include: a driving diode D3, a first driving resistor R8, and a second driving resistor R9, wherein: the first end of the driving diode D3 is coupled to the comparator unit 132, and the second end of the driving diode D3 is coupled to the first end of the first driving resistor R9 and the first end of the second driving resistor R8 respectively; the second end of the first driving resistor R9 is grounded; and the second end of the second driving resistor R8 is coupled to the limiting module 140.

[0093] Specifically, on the one hand, the initial comparison signal has a certain amplitude, and the amplitude of the initial comparison signal can be reduced by the driving voltage division effect of the first driving resistor R8 and the second driving resistor R9; on the other hand, by setting the driving diode D3, the flow direction of the comparison signal is from the comparison unit 132 to the limiting module 140, so that the comparison signal can act on the limiting module 140.

[0094] In some embodiments, the threshold voltage can be adjusted for different application scenarios to meet different scenario requirements.

[0095] For example, see below. Figure 2 The audio signal limiting circuit may further include: a voltage providing module 150, coupled to the comparison module 130, for providing the threshold voltage Vth, and the amplitude of the threshold voltage Vth is variable.

[0096] By making the amplitude of the threshold voltage Vth variable, the state of the comparison signal can be changed, thereby enabling flexible amplitude limiting based on different audio usage scenarios.

[0097] In this embodiment, the voltage supply module 150 may include: a voltage source (not shown), coupled to the voltage source, and a first voltage divider unit composed of a first voltage supply resistor R10, a second voltage supply resistor R11, and a third voltage supply resistor R12, wherein: the first end of the first voltage supply resistor R10 is coupled to the voltage source, the second end of the first voltage supply resistor R10 is coupled to the first end of the second voltage supply resistor R11, and the third end of the first voltage supply resistor R10 is grounded through the third voltage supply resistor R12; the second end of the second voltage supply resistor R11 is coupled to the comparison module 130; wherein the resistance value of the first voltage supply resistor R10 is variable.

[0098] In other words, with a fixed voltage source, changing the resistance of the first voltage supply resistor R10 can alter the voltage division ratio of the first voltage divider unit, thereby changing the threshold voltage. Thus, while keeping the amplitude of the audio conversion signal constant, the state of the comparison signal can be altered.

[0099] In some embodiments, the audio signal limiting circuit may further include a feedback module, which is coupled to the comparison module 130 and the limiting module 140 respectively, for providing a cutoff frequency to prevent self-excited oscillation.

[0100] For example, see Figure 2 The feedback module may include: a feedback capacitor C1, a first feedback resistor R13, and a second feedback resistor R14, wherein: the first end of the feedback capacitor C1 is coupled to the comparison module 130, the second end of the feedback capacitor C1 is coupled to the limiting module 140 and the first end of the second feedback resistor R14 through the first feedback resistor R13, and the second end of the second feedback resistor R14 is grounded, wherein the feedback capacitor C1 and the first feedback resistor R13 provide the cutoff frequency.

[0101] In this embodiment, the limiting module 140 may include: a switching unit and a limiting unit, wherein the limiting unit has the limiting resistor, wherein:

[0102] A switching unit is coupled to the comparison module 130 and the limiting unit, respectively. The limiting unit is coupled to the input terminal of the gain module 110. When the comparison signal has the first state, the switching unit is in the selected state, and the limiting unit is turned on through an optocoupler, so that the limiting resistor is connected to the input terminal of the gain module 110 in parallel. When the comparison signal has the second state, the switching unit is in the open state, so that the limiting unit is turned off through an optocoupler, so that the limiting resistor is disconnected from the input terminal of the gain module.

[0103] Specifically, when the comparison signal has a first state, it indicates that the amplitude of the audio amplified signal is greater than the set threshold voltage. The switching unit is in the selected state, and then the limiting unit is selected based on the optocoupler effect. Thus, the limiting resistor can be connected in parallel to the input terminal of the gain module 110 to change the transformation ratio of the second transformer unit, thereby reducing the amplitude of the audio signal.

[0104] When the comparison signal has the second state, it indicates that the amplitude of the audio signal meets the set threshold voltage, the switching unit is in the off state, and then based on the optocoupler effect, the limiting unit 144 is disconnected, the transformation ratio of the second transformer unit remains unchanged, and the amplitude of the audio amplified signal remains unchanged.

[0105] In some embodiments, the switching unit may include: a transistor Q1, the control terminal of which is coupled to the comparison module 130, the first terminal of which is coupled to the limiting unit 144, and the second terminal of which is grounded.

[0106] That is, the connection and disconnection of the limiting resistor are realized through the selection and switching off process of transistor Q1.

[0107] In some embodiments, the limiting unit may include an optocoupler and a first limiting resistor R16. The optocoupler includes a light-emitting diode D1 and a second limiting resistor R15. The first terminal of the light-emitting diode D1 is coupled to the switching unit, and the second terminal of the light-emitting diode D1 is coupled to the first terminal of the first limiting resistor R16. The second limiting resistor R15 is coupled to the input terminal of the gain module 110 in parallel. The second terminal of the first limiting resistor R16 is coupled to the gain module 110.

[0108] Specifically, when the switching unit is in the on state, the light-emitting diode D1 is in the working state, and the second limiting resistor R15 can be connected in parallel to the input terminal of the gain module 110, thereby changing the equivalent resistance of the input terminal of the gain module 110.

[0109] More specifically, when the light-emitting diode D1 is in operation, the second limiting resistor R15 and the second voltage divider resistor R2 are connected in parallel. As a result, with the first voltage divider resistor R1 remaining unchanged, the equivalent resistance at the input terminal of 110 is reduced, and the voltage obtained by voltage division is also reduced, thereby reducing the amplitude of the output audio amplification signal.

[0110] When the switching unit is in the ON state, the LED D1 is in the OFF state, and the voltage division ratio of the second voltage divider unit remains unchanged, thus maintaining the amplitude of the audio amplified signal.

[0111] It should be noted that for the description of other limiting branches, please refer to the description of the first limiting branch. For example, the second limiting branch may include: a gain module, a conversion module, a comparison module, and a limiting module. The specific structure and working principle of the gain module, conversion module, comparison module, and limiting module can be found in the description of the first limiting branch.

[0112] Accordingly, the gain module may include: a first voltage divider resistor R1A and a second voltage divider resistor R2A, a third operational amplifier OA4, a first gain resistor R3A and a second gain resistor R4A.

[0113] The conversion module may include: a second operational amplifier OA5, a first rectifier diode D1A and a second rectifier diode D2A; a first compensation resistor R5A, a second compensation resistor R6A and a third compensation resistor R7A.

[0114] In this embodiment, the comparison module may include: a first operational amplifier OA6, a driving diode D3A, a first driving resistor R8A, and a second driving resistor R9A.

[0115] The voltage supply module may include: a voltage source (not shown), coupled to the voltage source, and a first voltage divider unit consisting of a first voltage supply resistor R10A, a second voltage supply resistor R11A, and a third voltage supply resistor R12A.

[0116] The feedback module may include: a feedback capacitor C1A, a first feedback resistor R13A, and a second feedback resistor R14A.

[0117] The limiting module may include: transistor Q1A, optocoupler and first limiting resistor R16A, wherein the optocoupler includes: light-emitting diode D1A and second limiting resistor R15A.

[0118] This utility model also provides an audio device, which may include an audio signal limiting circuit as described in any of the foregoing embodiments.

[0119] Audio equipment may include components such as subwoofers, preamplifiers, and mixing consoles.

[0120] It is understood that the above description provides multiple embodiment solutions, and the optional methods described in each embodiment solution can be combined and cross-referenced with each other without conflict, thereby extending to a variety of possible embodiment solutions, all of which can be considered as the embodiment solutions disclosed in this disclosure.

[0121] While the embodiments disclosed herein are as described above, this utility model is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of this utility model; therefore, the scope of protection of this utility model should be determined by the scope defined in the claims.

Claims

1. An audio signal limiting circuit, characterized in that, include: At least one bandwidth-limiting branch, and any bandwidth-limiting branch includes: A gain module is used to receive an audio signal, amplify the audio signal, generate an amplified audio signal, and output the amplified audio signal, wherein the amplified audio signal has a voltage of the first type. A conversion module, coupled to the output of the gain module, is used to convert the voltage type of the audio amplified signal to obtain an audio converted signal, which has a second type of voltage. A comparison module, coupled to the conversion module, is used to output a comparison signal based on the magnitude between the voltage of the audio conversion signal and a threshold voltage, the comparison signal having a first state and a second state; The limiting module is coupled to both the comparison module and the gain module. When the comparison signal has the first state, it is in a strobe state, strobes the path between the gain module and the limiting module to connect the limiting resistor; and when the comparison signal has the second state, it is in a disconnect state, disconnects the path between the gain module and the limiting module to disconnect the limiting resistor.

2. The audio signal limiting circuit according to claim 1, characterized in that, The limiting module includes a switching unit and a limiting unit, wherein the limiting unit has the limiting resistor, and: A switching unit is coupled to both the comparison module and the limiting unit. The limiting unit is coupled to the input terminal of the gain module. When the comparison signal has the first state, the switching unit is in a selected state, and the limiting unit is turned on via an optocoupler, connecting the limiting resistor to the input terminal of the gain module in parallel. When the comparison signal has the second state, the switching unit is in an open state, and the limiting unit is turned off via an optocoupler, disconnecting the limiting resistor from the input terminal of the gain module.

3. The audio signal limiting circuit according to claim 2, characterized in that, The limiting module satisfies at least one or more of the following: The switching unit includes: a transistor, the control terminal of which is coupled to the comparison module, the first terminal of which is coupled to the limiting unit, and the second terminal of which is grounded; The limiting unit includes an optocoupler and a first limiting resistor. The optocoupler includes a light-emitting diode (LED) and a second limiting resistor. The first end of the LED is coupled to the switching unit, and the second end of the LED is coupled to the first end of the first limiting resistor. The second limiting resistor is coupled to the input terminal of the gain module in parallel. The second end of the first limiting resistor is coupled to the gain module.

4. The audio signal limiting circuit according to claim 1, characterized in that, The comparison module includes: a comparison unit and a driving unit, wherein: The comparison unit is coupled to the driving unit and the conversion module respectively, and is used to generate an initial comparison signal with a first state when the voltage of the audio conversion signal is greater than the threshold voltage, and to generate an initial comparison signal with a second state when the voltage of the audio conversion signal is less than the threshold voltage. The driving unit is coupled to the limiting module and is used to perform voltage division driving on the initial comparison signal to obtain the comparison signal.

5. The audio signal limiting circuit according to claim 4, characterized in that, The comparison module satisfies at least one or more of the following: The comparison unit includes a first operational amplifier, a first input terminal of the first operational amplifier is adapted to input the audio conversion signal, a second input terminal of the first operational amplifier is adapted to input the threshold voltage, and an output terminal of the first operational amplifier outputs the initial comparison signal. The driving unit includes a driving diode, a first driving resistor, and a second driving resistor, wherein: the first end of the driving diode is coupled to the comparator unit, and the second end of the driving diode is coupled to the first end of the first driving resistor and the first end of the second driving resistor, respectively; the second end of the first driving resistor is grounded; and the second end of the second driving resistor is coupled to the limiting module.

6. The audio signal limiting circuit according to claim 4 or 5, characterized in that, Also includes: A voltage supply module, coupled to the comparison module, is used to provide the threshold voltage, and the amplitude of the threshold voltage is variable; The feedback module is coupled to the comparison module and the limiting module respectively, and is used to provide the cutoff frequency; The voltage supply module includes: a voltage source, coupled to the voltage source, and a first voltage divider unit consisting of a first voltage supply resistor, a second voltage supply resistor, and a third voltage supply resistor, wherein: a first terminal of the first voltage supply resistor is coupled to the voltage source, a second terminal of the first voltage supply resistor is coupled to the first terminal of the second voltage supply resistor, and a third terminal of the first voltage supply resistor is grounded through the third voltage supply resistor; a second terminal of the second voltage supply resistor is coupled to the comparison module; wherein the resistance value of the first voltage supply resistor is variable; The feedback module includes a feedback capacitor, a first feedback resistor, and a second feedback resistor, wherein: the first end of the feedback capacitor is coupled to the comparison module; the second end of the feedback capacitor is coupled to the limiting module and the first end of the second feedback resistor through the first feedback resistor; and the second end of the second feedback resistor is grounded. The feedback capacitor and the first feedback resistor provide the cutoff frequency.

7. The audio signal limiting circuit according to claim 1, characterized in that, The conversion module includes: a conversion unit and a compensation unit, wherein: The conversion unit is coupled to the gain module and the compensation unit respectively, and is used to be in the on state when the audio amplification signal is in the positive half-cycle to convert the type of the audio amplification signal to obtain an audio conversion signal with a second type of voltage; and to be in the off state when the audio amplification signal is in the negative half-cycle to shut off the path between the audio amplification signal and the comparison module. The compensation unit is coupled to the comparison module and is used to compensate the audio conversion signal when the conversion unit is in the on state.

8. The audio signal limiting circuit according to claim 7, characterized in that, The conversion module satisfies at least one or more of the following: The conversion unit includes a second operational amplifier, a first rectifier diode, and a second rectifier diode, wherein: the first terminal of the second operational amplifier is coupled to the compensation unit and the first terminal of the first rectifier diode, respectively; the second terminal of the second operational amplifier is grounded; the third terminal of the second operational amplifier is coupled to the second terminal of the first rectifier diode and the first terminal of the second rectifier diode, respectively; and the second terminal of the second rectifier diode is coupled to the compensation unit. The compensation unit includes a first compensation resistor, a second compensation resistor, and a third compensation resistor, wherein: a first end of the first compensation resistor is coupled to the gain module; a second end of the first compensation resistor is coupled to a first end of the second compensation resistor and the conversion unit; a second end of the second compensation resistor is coupled to a first end of the third compensation resistor and the conversion unit; and a second end of the third compensation resistor is coupled to the comparison module.

9. The audio signal limiting circuit according to claim 1, characterized in that, The gain module includes: a second voltage divider unit and a gain unit, wherein: The second voltage divider unit is coupled to the gain unit and the limiting module respectively, and is adapted to perform voltage division processing on the audio signal according to the voltage division ratio of the second voltage divider unit and the limiting resistor to which the limiting module is connected, to obtain an audio voltage-divided signal; The gain unit is coupled to the limiting module and the conversion module respectively, and is used to amplify the audio voltage divider signal to generate the amplified audio signal.

10. The audio signal limiting circuit according to claim 9, characterized in that, The gain module satisfies at least one or more of the following: The second voltage divider unit includes: a first voltage divider resistor and a second voltage divider resistor, wherein a first terminal of the first voltage divider resistor is adapted to input the audio signal, and a second terminal of the first voltage divider resistor is coupled to the first terminal of the second voltage divider resistor and the limiting module; the second terminal of the second voltage divider resistor is coupled to the limiting module and grounded; The gain unit includes a third operational amplifier, a first gain resistor, and a second gain resistor. The first input terminal of the third operational amplifier is coupled to the second voltage divider unit and the limiting module, respectively. The second input terminal of the third operational amplifier is coupled to the first terminal of the first gain resistor and the first terminal of the second gain resistor, respectively. The second terminal of the first gain resistor is grounded. The second terminal of the second gain resistor is coupled to the output terminal of the third operational amplifier.

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