Loudspeaker impedance measuring circuit and loudspeaker impedance measuring system

Abstract

The embodiment of the utility model provides a loudspeaker impedance measurement circuit and a loudspeaker impedance measurement system, and the circuit comprises a first measurement circuit which is used for measuring the value of a current flowing through a loudspeaker; the second measuring circuit is used for measuring voltage values at the two ends of the loudspeaker; the first input end of the analog-to-digital conversion circuit is connected with the output end of the first measuring circuit, the second input end of the analog-to-digital conversion circuit is connected with the output end of the second measuring circuit, and the analog-to-digital conversion circuit is used for performing analog-to-digital conversion on the measured current value and voltage value to obtain a current digital quantity and a voltage digital quantity and transmitting the current digital quantity and the voltage digital quantity to the processor; and the input end of the processor is connected with the output end of the analog-to-digital conversion circuit, and the processor is used for calculating the impedance of the loudspeaker according to the current digital quantity and the voltage digital quantity.

Description

Technical Field

[0001] The present invention relates to the field of loudspeaker technology, and in particular to a loudspeaker impedance measurement circuit and a loudspeaker impedance measurement system. Background Art

[0002] The matching of power amplifiers (PAs) and speakers ensures good sound quality. If the output power of the PA does not match the load capacity of the speaker, it may cause speaker overload and damage. If the impedance of the speaker does not match the rated output impedance of the PA, it may cause amplifier overload and damage.

[0003] In order to protect the speakers, ensure sound quality and improve efficiency, the power amplifier and the speakers need to be adapted. However, in the field of power amplifiers, there is little testing of the speakers, and it is impossible to detect whether the power amplifier and the speakers are matched. When checking the matching situation, professionals are often required to disassemble the machine for inspection, which will cause unpredictable risks to the equipment and increase the difficulty of after-sales maintenance.

[0004] Therefore, a speaker impedance measurement circuit and a speaker impedance measurement system are provided to help accurately detect the impedance of the speaker, facilitate the adaptation between the power amplifier and the speaker, ensure the transmission quality of the audio signal, and thus improve the sound quality of the speaker. Utility Model Content

[0005] One or more embodiments of the present specification provide a speaker impedance measurement circuit, which includes: a first measurement circuit for measuring the current value flowing through the speaker; a second measurement circuit for measuring the voltage value at both ends of the speaker; an analog-to-digital conversion circuit, wherein a first input end of the analog-to-digital conversion circuit is connected to an output end of the first measurement circuit, and a second input end of the analog-to-digital conversion circuit is connected to an output end of the second measurement circuit, and is used to perform analog-to-digital conversion on the measured current value and voltage value to obtain a current digital quantity and a voltage digital quantity and transmit them to a processor; and a processor, wherein an input end of the processor is connected to an output end of the analog-to-digital conversion circuit, and the processor is used to calculate the impedance of the speaker based on the current digital quantity and the voltage digital quantity.

[0006] In some embodiments, the first measurement circuit includes a sampling resistor and a sampling circuit. The sampling resistor is connected in series between the speaker and the power amplifier. The sampling circuit is used to sense the current flowing through the sampling resistor to obtain an output voltage. The output voltage is positively correlated with the current value. The input end of the second measurement circuit is connected between the sampling resistor and the speaker.

[0007] In some embodiments, the sampling circuit includes a differential amplifier for suppressing zero-point drift and interference in the differential input signal. A first input terminal and a second input terminal of the differential amplifier are respectively connected to two ends of the sampling resistor.

[0008] In some embodiments, the sampling circuit further includes a first operational amplifier and a first low-pass filter, the operational amplifier being used to amplify the output signal of the differential amplifier, the non-inverting input of the first operational amplifier being connected to the output of the differential amplifier, and the output of the differential amplifier being connected to the non-inverting input of the first operational amplifier via the first low-pass filter.

[0009] In some embodiments, the second measurement circuit includes an attenuation circuit and a second operational amplifier. The attenuation circuit is used to reduce the strength of the signal input to the second measurement circuit. The input end of the attenuation circuit is connected between the sampling resistor and the speaker. The output end of the attenuation circuit is connected to the second operational amplifier. The second operational amplifier is used to reduce the strength of the signal input to the analog-to-digital conversion circuit.

[0010] In some embodiments, the second measurement circuit further includes a feedback capacitor, the non-inverting input terminal of the second operational amplifier is connected to ground, and the feedback capacitor is arranged between the inverting input terminal and the output terminal of the first operational amplifier.

[0011] In some embodiments, the analog-to-digital conversion circuit includes an analog-to-digital conversion chip, the output end of the first measurement circuit is connected to the first input end of the analog-to-digital conversion chip through a second filter; the output end of the second measurement circuit is connected to the second input end of the analog-to-digital conversion chip through a third filter.

[0012] In some embodiments, the interrupt pin, serial communication port, and audio serial port of the analog-to-digital conversion chip are connected to the processor.

[0013] One or more embodiments of this specification provide a speaker impedance measurement system, which includes a speaker, a power amplifier, and a speaker impedance measurement circuit. The speaker impedance measurement circuit is provided between an output end of the power amplifier and an input end of the speaker.

[0014] In some embodiments, the power amplifier includes a first output terminal and a second output terminal. A first speaker impedance measurement circuit is provided between the first output terminal and the input terminal of the first speaker, and a second speaker impedance measurement circuit is provided between the second output terminal and the input terminal of the second speaker. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] This specification will be further described in the form of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting, and in these embodiments, like numbers represent like structures, wherein:

[0016] Figure 1 is a schematic structural diagram of a loudspeaker impedance measurement circuit according to some embodiments of this specification;

[0017] Figure 2is a structural diagram of the connection relationship of the sampling resistors according to some embodiments of this specification;

[0018] Figure 3 is a schematic structural diagram of a sampling circuit according to some embodiments of this specification;

[0019] Figure 4 is a structural schematic diagram of a second measurement circuit according to some embodiments of this specification;

[0020] Figure 5 It is a structural schematic diagram of an analog-to-digital conversion circuit according to some embodiments of this specification. DETAILED DESCRIPTION

[0021] To more clearly illustrate the technical solutions of the embodiments of this specification, the following briefly describes the drawings required for describing the embodiments. Obviously, the drawings described below are merely examples or embodiments of this specification. Those skilled in the art can apply this specification to other similar scenarios based on these drawings without inventive effort. Unless otherwise apparent from the context or otherwise noted, the same reference numerals in the figures represent the same structure or operation.

[0022] It should be understood that the terms "system," "device," "unit," and / or "module" used herein are a method for distinguishing different components, elements, parts, portions, or assemblies at different levels. However, if other terms can achieve the same purpose, the terms may be replaced by other expressions.

[0023] As used in this specification and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not refer to the singular but also include the plural. Generally speaking, the terms "comprises" and "include" only indicate the inclusion of the steps and elements specifically identified, and these steps and elements do not constitute an exclusive list. A method or apparatus may also include other steps or elements.

[0024] Flowcharts are used throughout this specification to illustrate the operations performed by systems according to embodiments of this specification. It should be understood that preceding or following operations do not necessarily need to be performed in exact order. Instead, the steps may be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more operations may be removed from these processes.

[0025] Impedance matching is paramount for amplifier and speaker compatibility. The speaker is the primary load for the amplifier, and its nominal (or rated) impedance should be equal to or similar to the amplifier's rated output impedance. If the speaker's rated impedance is greater than the amplifier's rated output impedance, the amplifier's actual output power will be less than the rated output power. If the speaker's rated impedance is less than the amplifier's rated output impedance, the audio system will function, but the amplifier may be overloaded, requiring comprehensive overcurrent protection. Impedance matching requirements are even stricter for tube amplifiers. Currently, medium- and high-power audio systems do not support internal current and voltage signal sampling. This is because sampling current and voltage signals at high currents would make the integrated design of the power amplifier chip too large and generate excessive heat, thus affecting the stability of the audio product. While small audio power amplifier chips can integrate current and voltage signal sampling, most use single-channel feedback, making them difficult to meet the requirements of existing audio systems.

[0026] In view of this, some embodiments of this specification provide a speaker impedance measurement circuit and a speaker impedance measurement system. By measuring the current value flowing through the speaker and the voltage value at both ends of the speaker, the impedance of the speaker can be calculated efficiently and accurately, which is beneficial for analyzing whether the impedance of the power amplifier and the speaker matches, and helps to adjust the mismatched audio system, protecting the equipment while improving the user experience.

[0027] In some embodiments, the speaker impedance measurement circuit can be applied to the design and manufacture of speakers, audio system debugging and maintenance, and other fields. By accurately testing the speaker impedance, the power amplifier and speaker can be matched, and the sound quality and stability of the audio system can be guaranteed.

[0028] Figure 1 This is a structural diagram of a loudspeaker impedance measurement circuit according to some embodiments of this specification.

[0029] like Figure 1 As shown, the speaker impedance measurement circuit 100 may include a first measurement circuit 120 , a second measurement circuit 130 , an analog-to-digital conversion circuit 140 , and a processor 150 .

[0030] The first measurement circuit 120 is a circuit for measuring the value of the current flowing through the speaker 170 .

[0031] In some embodiments, the first measurement circuit 120 may measure the current value flowing through the speaker 170 by sensing the voltage drop of the branch where the speaker 170 is located.

[0032] In some embodiments, the first measurement circuit 120 can perform current sampling using components such as a Hall current sensor and a sampling resistor 110. The Hall current sensor and the sampling resistor 110 can be disposed between the speaker 170 and the power amplifier 160, and the sampling resistor 110 can also be disposed between the output terminal of the speaker 170 and the ground terminal.

[0033] The power amplifier 160 is used to amplify the weak electrical signal from the signal source to drive the speaker 170 to produce sound. For example, the power amplifier 160 includes various power amplifier 160 circuits, audio power amplifier chips, etc.

[0034] In some embodiments, the power amplifier 160 is a medium-power audio power amplifier and / or a high-power audio power amplifier, a class-D power amplifier, etc.

[0035] In some embodiments, the power amplifier 160 may be an IRS2452 chip.

[0036] In some embodiments, the first measurement circuit 120 may include a sampling resistor 110 and a sampling circuit, wherein the sampling resistor 110 is connected in series between the speaker 170 and the power amplifier 160. For more information about the sampling resistor, see Figure 2 For more information about sampling circuits, see Figure 3 Related description.

[0037] The second measurement circuit 130 is a circuit for measuring a voltage value across the speaker 170 .

[0038] In some embodiments, the second measurement circuit 130 can perform voltage sampling using components such as a Hall voltage sensor, an isolation amplifier, an optocoupler, and a transformer. For example, the Hall voltage sensor can be connected in parallel across the speaker 170, and the voltage across the speaker 170 can be measured by generating an electromotive force through a semiconductor chip in the Hall voltage sensor.

[0039] In some embodiments, the second measurement circuit 130 may include an attenuation circuit and a second operational amplifier. The attenuation circuit is used to reduce the strength of the signal input to the second measurement circuit 130. The input of the attenuation circuit is connected between the sampling resistor 110 and the speaker 170, and the output of the attenuation circuit is connected to the second operational amplifier. The second operational amplifier is used to reduce the strength of the signal input to the analog-to-digital conversion circuit 140.

[0040] In some embodiments, the attenuation circuit may include an attenuator, such as an L-type, T-type, bridge-T-type, π-type, or other attenuator.

[0041] In some embodiments, the attenuation circuit may be a voltage attenuator composed of resistors, which can attenuate the input signal of the second measurement circuit 130 by means of resistor voltage division.

[0042] For more information about the second measurement circuit 130, please refer to Figure 4 Related description.

[0043] The analog-to-digital conversion circuit 140 is used to perform analog-to-digital conversion on the measured current value and voltage value to obtain a digital current value and a digital voltage value.

[0044] In some embodiments, the analog-to-digital conversion circuit 140 may include an analog-to-digital conversion chip.

[0045] In some embodiments, the analog-to-digital conversion circuit 140 may include multiple analog signal inputs. A first input terminal of the analog-to-digital conversion circuit 140 is connected to an output terminal of the first measurement circuit 120, a second input terminal of the analog-to-digital conversion circuit 140 is connected to an output terminal of the second measurement circuit 130, and an output terminal of the analog-to-digital conversion circuit 140 is connected to a processor 150 for transmitting digital current and digital voltage values ​​to the processor 150. For more information about the analog-to-digital conversion circuit 140, see Figure 5 Related description.

[0046] The processor 150 is configured to calculate the impedance of the speaker 170 according to the current digital value and the voltage digital value.

[0047] In some embodiments, the processor 150 is a circuit that executes instructions and processes data, and can perform corresponding control content according to the instructions. In some embodiments, the processor 150 can be a microcontroller. A microcontroller, also known as a single-chip microcomputer, can be a chip-level computer that can perform corresponding control content according to the instructions. In some embodiments, the processor 150 can be a QCC5100 series chip.

[0048] In some embodiments, the microcontroller unit can process data according to instructions and generate corresponding control signals. In some embodiments, the microcontroller unit may also include other types of processors, which will not be described in detail here. As an example only, when the processor 150 is a DSP, after receiving the digital value of current and the digital value of voltage, the DSP can calculate the current impedance of the speaker 170 and search the memory for control content corresponding to the current impedance. For example, the DSP can generate a control signal based on the difference between the current impedance and the preset impedance to cut off the output of the power amplifier or adjust the output of the power amplifier. For another example, the DSP can send a control signal based on the temperature of the power amplifier 160 to adjust the working state of the power amplifier 160.

[0049] In some embodiments, the processor 150 has a feedback signal input terminal and a control output terminal, the control output terminal is used to output an adjustment signal to cut off the output of the power amplifier or adjust the output of the power amplifier; the output terminal of the analog-to-digital conversion circuit 140 is connected to the feedback signal input terminal of the processor 150.

[0050] For example, power amplifier 160 can amplify the power of an audio signal and output it to speaker 170. Second measurement circuit 130 detects the voltage across speaker 170, and first measurement circuit 120 detects the current output by power amplifier 160. Analog-to-digital conversion circuit 140 converts the detected current and voltage values ​​into corresponding digital current and voltage quantities, respectively, and outputs them to processor 150. Processor 150 generates an adjustment signal based on the digital current and voltage quantities, ultimately enabling real-time adjustment of the signal output to speaker 170, thereby achieving a dynamic balance between the acoustic performance and reliability of speaker 170. By forming a feedback circuit between first measurement circuit 120, second measurement circuit 130, analog-to-digital conversion circuit 140, and processor 150, feedback adjustment of power amplifier 160 is implemented, thereby achieving matching between speaker 170 and power amplifier 160.

[0051] In some embodiments, the magnitude of the signal input to the power amplifier 160 may be adjusted by filtering or adjusting the voltage.

[0052] In some embodiments of the present specification, the impedance of the speaker is determined by the first measurement circuit and the second measurement circuit, which can help control the signal flow inside the adjustment processor to achieve different power levels under different loads; controlling the power amplifier to require different output powers when matching speakers with different impedances helps prevent signal overload and provides overcurrent protection for the speaker. It is suitable for different application scenarios, energy-saving and efficient, and the circuit has the characteristics of high precision, fast response, low latency, and strong anti-interference ability.

[0053] Figure 2 Schematic diagram of the connection relationship of sampling resistors according to some embodiments of this specification.

[0054] In some embodiments, as Figure 2 As shown, the sampling resistor is resistor R1, the sampling circuit includes resistors R4 and R5, and the second measurement circuit includes resistor R2.

[0055] A sampling resistor is a resistor used in circuits to collect signals, measure current, and measure voltage. For example, a sampling resistor can convert a portion of the current or voltage in a circuit into a measurable signal by dividing it with resistors. A sampling resistor can be connected in series to collect current signals or in parallel to collect voltage signals.

[0056] In some embodiments, the resistance of the sampling resistor can be determined according to the range of the speaker and the current size.

[0057] In some embodiments, the resistor R1 is disposed in a branch of the speaker. For example, the resistor R1 may be connected in series to an output terminal of a power amplifier, or connected in series to an input terminal of a speaker.

[0058] In some embodiments, as Figure 2 As shown, a first end of resistor R1 is connected to one end of resistor R5, and the other end of resistor R5 serves as a first input port (e.g., CH2_IS1) of differential amplifier U1. A second end of resistor R1 is connected to one end of resistor R4, and the other end of resistor R4 serves as a second input port (e.g., CH2_IS2) of the differential amplifier. In some embodiments, resistor R5 can be a sliding rheostat.

[0059] In some embodiments, resistor R2 can be used as an attenuator to divide the voltage of the signal input to the second measurement circuit and attenuate the signal strength. One end of resistor R2 is connected to the second end of resistor R1, and the other end of resistor R2 serves as the input port (e.g., CH2_VCS) of the second operational amplifier U3. For more information about the second operational amplifier U3, please refer to Figure 4 Related description.

[0060] In some embodiments, the other end of the resistor R2 is further connected to the signal ground through the resistor R3. The resistor R3 is a reserved matching design and can be adjusted or replaced with magnetic beads according to experimental conditions.

[0061] In some embodiments of the present specification, a relatively accurate measurement result can be obtained by using a sampling resistor. Since the resistance value of the sampling resistor is relatively low, the current and voltage measurements will not significantly affect the normal operation of the circuit.

[0062] Figure 3 Schematic diagram of a sampling circuit according to some embodiments of this specification.

[0063] The sampling circuit is used to sense the current flowing through the sampling resistor to obtain an output voltage, and the output voltage is positively correlated with the current value flowing through the speaker.

[0064] In some embodiments, as Figure 3 As shown, the sampling circuit includes a differential amplifier U1, whose first input terminal (e.g., CH2_IS1) and second input terminal (e.g., CH2_IS2) are respectively connected to the two ends of resistor R1. Differential amplifier U1 can effectively suppress common-mode interference from complex environments on the sampling circuit.

[0065] In some embodiments, the REF- pin of the differential amplifier U1 is connected to the signal ground (eg, Figure 3 In some embodiments, the REF+ pin of the differential amplifier U1 is connected to the signal ground (e.g., Figure 3 In some embodiments, the +Vs pin of the differential amplifier U1 is connected to the first power supply (eg, Figure 3 In some embodiments, the -Vs pin of the differential amplifier U1 is connected to a second power supply (e.g. Figure 3 In some embodiments, the +IN pin of differential amplifier U1 is connected to the first input terminal of differential amplifier U1 (e.g., CH2_IS1). In some embodiments, the -IN pin of differential amplifier U1 is connected to the second input terminal of differential amplifier U1 (e.g., CH2_IS2). In some embodiments, the NC pin of differential amplifier U1 is left floating.

[0066] For example, the differential amplifier U1 can be an AD8479 chip, which is a precision differential amplifier with a very high input common-mode voltage range. It can accurately measure differential signals under high common-mode voltage conditions of up to +600V, thereby improving measurement accuracy.

[0067] In some embodiments, the OUT pin of the differential amplifier U1 is connected to the first operational amplifier.

[0068] In some embodiments, the gain of the differential amplifier U1 can be configured by selecting appropriate resistors R4 and R5.

[0069] In some embodiments, the sampling circuit includes a first operational amplifier U2 for amplifying the output signal of the differential amplifier.

[0070] In some embodiments, the non-inverting input of the first operational amplifier U2 is connected to the OUT pin of the differential amplifier U1 through a first low-pass filter. In some embodiments, a first feedback circuit is connected between the inverting input and the output of the first operational amplifier U2.

[0071] In some embodiments, the first feedback circuit includes resistors R10 and R11 connected in series to form a first series circuit, and resistors R8 and R9 connected in parallel to form a first parallel circuit. One end of the first series circuit is connected to one end of the first parallel circuit, the other end of the first series circuit is connected to the output of the first operational amplifier U2, and the other end of the first parallel circuit is connected to the signal ground. The inverting input of the first operational amplifier U2 is connected to the connection point between resistors R10 and R11. Resistor R8 is a sliding rheostat.

[0072] The first low-pass filter is a circuit for selecting the signal frequency in the first measurement circuit. The first low-pass filter can effectively eliminate high-order harmonics and suppress signals of useless frequencies.

[0073] In some embodiments, the first low-pass filter may be a second-order low-pass filter circuit.

[0074] In some embodiments, the first low-pass filter may be a voltage-controlled voltage filter circuit, which includes a resistor R6, a resistor R7, a capacitor C1, and a capacitor C2.

[0075] In some embodiments, the non-inverting input terminal of the first operational amplifier U2 is connected to the signal ground through the capacitor C2; it is connected to the OUT pin of the differential amplifier U1 through the series-connected resistors R6 and R7; the output terminal of the first operational amplifier U2 introduces positive feedback through the capacitor C1, one end of the capacitor C1 is connected to the connection point between the resistors R6 and R7, and the other end of the capacitor C1 is connected to the output terminal of the first operational amplifier U2.

[0076] In some embodiments, the positive power supply terminal of the first operational amplifier U2 is connected to a third power supply (not shown in the figure), and the negative power supply terminal is connected to a fourth power supply (not shown in the figure).

[0077] Through the voltage-controlled voltage filter circuit, C1 in a simple second-order low-pass filter circuit can be connected to the output of the operational amplifier, and negative feedback and positive feedback can be introduced into the circuit at the same time. By setting the parameters reasonably, the amplification ability of the signal at the cutoff frequency can be improved, and self-oscillation caused by excessive positive feedback can be avoided.

[0078] In some embodiments, the output end of the first operational amplifier U2 is connected to a first output filter circuit, and the first output filter circuit is used to filter out interference and noise of high-frequency signals in the signal output by the first operational amplifier U2.

[0079] In some embodiments, the first output filter circuit is a passive filter circuit, the input end of the first output filter circuit is connected to the output end of the first operational amplifier U2, and the output end of the first output filter circuit (such as Figure 5 ISENSE L) and the first input terminal of the analog-to-digital conversion circuit (such as Figure 5 VINL2 / VIN1M) connections as shown.

[0080] In some embodiments, the first output filter circuit includes a resistor R12 and a capacitor C3. One end of the resistor R12 is connected to the output terminal of the first operational amplifier U2, the other end of the resistor R12 is connected to the capacitor C3, and the other end of the resistor R12 is also connected to the first input terminal of the analog-to-digital conversion circuit.

[0081] Figure 4is a structural schematic diagram of a second measurement circuit according to some embodiments of this specification.

[0082] In some embodiments, as Figure 4 As shown, the second measurement circuit further includes a second operational amplifier U3.

[0083] In some embodiments, the CH1_VCS port is connected to the inverting input of the second operational amplifier U3 via a resistor R13. The connection point between the CH1_VCS port and resistor R13 is connected to the first end of a capacitor C4, and the second end of capacitor C4 is connected to a signal ground. Capacitor C4 is used to reduce noise and interference in the signal input to the second operational amplifier U3. The non-inverting input of the second operational amplifier U3 is connected to a signal ground. In some embodiments, a second feedback circuit is connected between the inverting input and the output of the second operational amplifier U3.

[0084] In some embodiments, the second feedback circuit includes a resistor R14 , wherein an inverting input terminal of the second operational amplifier U3 is connected to one end of the resistor R14 , and the other end of the resistor R14 is connected to an output terminal of the second operational amplifier U3 .

[0085] In some embodiments, the positive power supply terminal of the second operational amplifier U3 is connected to a fifth power supply (eg, Figure 4 +13.5V in the negative power supply terminal is connected to the sixth power supply (such as Figure 4 -13.5V in the output).

[0086] In some embodiments, the output end of the second operational amplifier U3 is connected to a second output filter circuit, and the second output filter circuit is used to filter out interference and noise of high-frequency signals in the signal output by the second operational amplifier U3.

[0087] In some embodiments, the second output filter circuit is a passive filter circuit, the input end of the second output filter circuit is connected to the output end of the second operational amplifier U3, and the output end of the second output filter circuit (such as Figure 5 VSENSE L) and the second input terminal of the analog-to-digital conversion circuit (such as Figure 5 VINR2 / VIN2M) connections as shown.

[0088] In some embodiments, the second output filter circuit includes a resistor R15 and a capacitor C6. One end of the resistor R15 is connected to the output terminal of the second operational amplifier U3, the other end of the resistor R15 is connected to the capacitor C6, and the other end of the resistor R15 is also connected to the second input terminal of the analog-to-digital conversion circuit.

[0089] Figure 5 It is a structural schematic diagram of an analog-to-digital conversion circuit according to some embodiments of this specification.

[0090] In some embodiments, as Figure 5 As shown, the analog-to-digital conversion circuit includes an analog-to-digital conversion chip U4.

[0091] In some embodiments, the power amplifier has a first output terminal and a second output terminal, the first output terminal is used to output the audio signal of the first channel, the second output terminal is used to output the audio signal of the second channel, the first speaker is used to receive and play the audio signal of the first channel, and the second speaker is used to receive and play the audio signal of the second channel. The speaker impedance measurement system also includes a first speaker impedance measurement circuit and a second speaker impedance measurement circuit. The first speaker impedance measurement circuit is arranged on a branch from the first output terminal of the power amplifier to the input terminal of the first speaker, and is used to detect the impedance of the first speaker. The second speaker impedance measurement circuit is arranged on a branch from the second output terminal of the power amplifier to the input terminal of the second speaker, and is used to detect the impedance of the second speaker.

[0092] The first speaker impedance measurement circuit and the second speaker impedance measurement circuit can be implemented by the speaker impedance measurement circuits shown in some embodiments of this specification.

[0093] In some embodiments, as Figure 5 As shown, the first speaker impedance measurement circuit includes a first measurement circuit and a second measurement circuit. The first measurement circuit is used to measure the current value flowing through the first speaker; the second measurement circuit is used to measure the voltage value across the first speaker. The output port ISENSE L of the first measurement circuit is connected to the VINL2 / VIN1M pin of the analog-to-digital conversion chip through the first input filter circuit; the output port VSENSE L of the second measurement circuit is connected to the VINR2 / VIN2M pin of the analog-to-digital conversion chip through the second input filter circuit.

[0094] The first input filter circuit is used to filter out interference and noise in the output signal of the first measurement circuit.

[0095] The second input filter circuit is used to filter out interference and noise in the output signal of the second measurement circuit.

[0096] In some embodiments, as Figure 5 As shown, the second speaker impedance measurement circuit includes a third measurement circuit and a fourth measurement circuit. The third measurement circuit is used to measure the current value flowing through the second speaker; the fourth measurement circuit is used to measure the voltage value across the second speaker. The output port ISENSE R of the third measurement circuit is connected to the VINL1 / VIN1P pin of the analog-to-digital conversion chip through the third input filter circuit; the output port VSENSE R of the fourth measurement circuit is connected to the VINR1 / VIN2P pin of the analog-to-digital conversion chip through the fourth input filter circuit.

[0097] The third input filter circuit is used to filter out interference and noise in the output signal of the third measurement circuit.

[0098] The fourth input filter circuit is used to filter out interference and noise in the output signal of the fourth measurement circuit.

[0099] In some embodiments, the analog-to-digital conversion chip U4 is an audio ADC. For example, the analog-to-digital conversion chip U4 can be a PCM1863 chip. The analog-to-digital conversion chip U4 is configured with multiple independent ADC channels. For example, the analog-to-digital conversion chip U4 includes 4 analog inputs (such as Figure 5 As shown, the four pins VINL1 / VIN1P, VINR1 / VIN2P, VINL2 / VIN1M, and VINR2 / VIN2M of U4 are used as analog inputs).

[0100] In some embodiments, the VINL2 / VIN1M pin of the analog-to-digital conversion chip U4 is connected to the output end of the first output filter circuit through the second filter; the VINR2 / VIN2M pin of the analog-to-digital conversion chip U4 is connected to the output end of the second output filter circuit through the third filter; the Mic Bias pin of the analog-to-digital conversion chip U4 is connected to the ground terminal (such as Figure 5 The Mic Bias pin of the analog-to-digital conversion chip U4 is connected to the ground terminal through the capacitor C13; the VREF pin of the analog-to-digital conversion chip U4 is connected to the ground terminal through the capacitor C14; the AGND pin and DGND pin of the analog-to-digital conversion chip U4 are connected to the ground terminal; the AVDD pin of the analog-to-digital conversion chip U4 is connected to the sixth power supply (such as Figure 5 The 3.3V power supply shown in FIG1 is connected to the AVDD pin of the analog-to-digital conversion chip U4, and the AVDD pin of the analog-to-digital conversion chip U4 is also connected to the ground terminal through two parallel capacitors C15 and C16; the LDO pin of the analog-to-digital conversion chip U4 is connected to the ground terminal through a capacitor C17; the DVDD pin of the analog-to-digital conversion chip U4 is connected to the seventh power supply (such as Figure 5 The DVDD pin of the analog-to-digital conversion chip U4 is also connected to the ground terminal through the capacitor C18; the IOVDD pin of the analog-to-digital conversion chip U4 is connected to the seventh power supply (such as Figure 5 The DVDD pin of the analog-to-digital conversion chip U4 is also connected to the ground terminal through the capacitor C19; the SCKI pin of the analog-to-digital conversion chip U4 is connected to the processor (such as Figure 5 The MD0 pin of the analog-to-digital conversion chip U4 is connected to the ground terminal through a resistor R27; the MS / AD pin of the analog-to-digital conversion chip U4 is connected to the ground terminal through a resistor R28; the MC / SCL pin of the analog-to-digital conversion chip U4 is connected to the processor (such as Figure 5The MOSI / SDA pin of the analog-to-digital converter chip U4 is connected to the processor (such as Figure 5 The MISO / GPIO 0 pin of the analog-to-digital converter chip U4 is connected to the processor (such as Figure 5 The GPIO1 / IntA / DMIN pin of the analog-to-digital conversion chip U4 is connected to the ground terminal through two series resistors R31 and R32, and the connection point between the resistors R31 and R32 is connected to the processor (such as Figure 5 The DOUT pin of the analog-to-digital conversion chip U4 is connected to the processor (such as Figure 5 The BCK pin of the analog-to-digital converter chip U4 is connected to the processor (such as Figure 5 The LRCK pin of the analog-to-digital converter chip U4 is connected to the processor (such as Figure 5 SAI5_RXFS port as shown) connection.

[0101] In some embodiments, as Figure 5 As shown, the first input filter circuit includes a resistor R17, a capacitor C7, a resistor R18, and a capacitor C10, wherein the output port ISENSE L of the first measurement circuit is connected to the VINL2 / VIN1M pin of the analog-to-digital conversion chip through the capacitor C7 and the resistor R18 connected in series, and the output port ISENSE L of the first measurement circuit is also connected to the ground terminal through the resistor R17, and the connection point between the resistor R18 and the VINL2 / VIN1M pin of the analog-to-digital conversion chip is connected to the ground terminal through the capacitor C10.

[0102] Among them, C7 is an electrolytic capacitor, which is used for coupling between the first measurement circuit and the analog-to-digital conversion circuit to prevent the static operating points of the front and rear circuits from affecting each other and to prevent excessive loss of low-frequency components in the signal. The capacitance value of the electrolytic capacitor C7 is relatively large.

[0103] In some embodiments, as Figure 4 As shown, the second input filter circuit includes a resistor R16, a capacitor C8, a resistor R19, and a capacitor C11. The output port VSENSE L of the second measurement circuit is connected to the VINL2 / VIN2M pin of the analog-to-digital conversion chip via the series-connected capacitor C8 and resistor R19. The output port VSENSE L of the second measurement circuit is also connected to ground via resistor R16. The connection point between resistor R19 and the VINR2 / VIN2M pin of the analog-to-digital conversion chip is connected to ground via capacitor C11. C8 is an electrolytic capacitor.

[0104] In some embodiments, the third input filter circuit includes a resistor R23, a capacitor C22, a resistor R20, and a capacitor C9. The output port ISENSE R of the third measurement circuit is connected to the VINL1 / VIN1P pin of the analog-to-digital converter chip via the series-connected capacitors C22 and R20. The output port ISENSE R of the third measurement circuit is also connected to ground via the resistor R23. The connection point between the resistor R20 and the VINL1 / VIN1P pin of the analog-to-digital converter chip is connected to ground via the capacitor C9. C22 is an electrolytic capacitor.

[0105] In some embodiments, the fourth input filter circuit includes a resistor R22, a capacitor C23, a resistor R21, and a capacitor C12. The output port VSENSE R of the fourth measurement circuit is connected to the VINL1 / VIN2P pin of the analog-to-digital conversion chip via the series-connected capacitor C23 and resistor R21. The output port VSENSE R of the fourth measurement circuit is also connected to ground via resistor R22. The connection point between resistor R21 and the VINR1 / VIN2P pin of the analog-to-digital conversion chip is connected to ground via capacitor C12. C23 is an electrolytic capacitor.

[0106] In some embodiments, the speaker impedance measurement system further includes a temperature acquisition circuit, which is disposed next to the power amplifier. The temperature acquisition circuit is used to collect the current temperature of the power amplifier and send a signal related to the current temperature of the power amplifier to the processor through an analog-to-digital conversion chip.

[0107] A temperature acquisition circuit is a sensing module that converts sensed temperature into a usable output signal. In some embodiments, the temperature acquisition circuit can be incorporated into a speaker impedance measurement system. Furthermore, the temperature acquisition circuit can be located at an input terminal of an analog-to-digital conversion chip. In some embodiments, the temperature acquisition circuit can be a temperature sensor or thermistor, and the signal output by the temperature acquisition circuit can change with temperature changes. Exemplarily, the temperature acquisition circuit can utilize analog communication. This specification does not specifically limit the type of temperature acquisition circuit.

[0108] In some embodiments, by measuring the current temperature of the power amplifier, the speaker impedance measurement system can monitor the operating status of the power amplifier in real time to prevent the amplifier from overheating and causing malfunction. In some embodiments, when the power amplifier temperature is too high, the processor can take control measures, such as controlling the power amplifier to stop operating.

[0109] In some embodiments, the temperature acquisition circuit may include a thermistor. The temperature acquisition circuit may convert the real-time analog voltage value of the thermistor into a digital voltage value via an analog-to-digital conversion chip and transmit the converted value to a processor. The processor then determines the resistance of the thermistor based on the real-time digital voltage value of the thermistor. The resistance of the thermistor changes with temperature, and temperature can be reflected by the resistance of the thermistor. Therefore, the resistance of the thermistor can be calculated by calculating the voltage value of the thermistor, thereby determining the current temperature of the power amplifier.

[0110] In some embodiments, as Figure 5 As shown, the temperature acquisition circuit includes a first voltage divider circuit and an eighth power supply, wherein the temperature acquisition circuit is used to collect the divided voltage value of the first voltage divider circuit to calculate the current temperature of the power amplifier, and the eighth power supply provides a voltage source for the temperature acquisition circuit.

[0111] like Figure 5 As shown, the first voltage divider circuit includes a voltage divider resistor R37 and a resistor U5, and the eighth power supply is 3.3V. U5 is a thermistor; by collecting the divided voltage value of the thermistor U5, the resistance of the thermistor U5 can be determined, thereby reflecting the temperature change of the power amplifier. A temperature filter circuit is also included to filter the signal output by the temperature collection circuit to the analog-to-digital conversion chip.

[0112] In some embodiments, the temperature filtering circuit may include a resistor R26 and a capacitor C21, the VINL3 / VIN4P pin of the analog-to-digital conversion chip is connected to the first end of the thermistor U5, the connection point between the VINL3 / VIN4P pin and the first end of the thermistor U5 is connected to one end of the parallel circuit composed of the resistor R26 and the capacitor C21, the other end of the parallel circuit composed of the resistor R26 and the capacitor C21 is connected to the ground end, and the second end of the thermistor U5 is connected to the seventh power supply through the series resistor R37.

[0113] In some embodiments, as Figure 5 As shown, the VINR3 / VIN3P pin of the analog-to-digital conversion chip is connected to the processor (such as Figure 5 The connection point between the VINR3 / VIN3P pin of the analog-to-digital converter chip and resistor R24 ​​is connected to one end of a parallel circuit consisting of resistor R25 and capacitor C20. The other end of this parallel circuit is connected to ground. Resistor R26 and capacitor C21 form a parallel filtering circuit to filter the signal input to the VINR3 / VIN3P pin of the analog-to-digital converter chip.

[0114] While the basic concepts have been described above, it will be apparent to those skilled in the art that the detailed disclosure is merely illustrative and does not limit this specification. Although not explicitly stated herein, various modifications, improvements, and revisions to this specification may be made by those skilled in the art. Such modifications, improvements, and revisions are suggested in this specification and remain within the spirit and scope of the exemplary embodiments of this specification.

[0115] This specification also uses specific terms to describe the embodiments of this specification. For example, "one embodiment," "an embodiment," and / or "some embodiments" refer to a feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and noted that references to "one embodiment," "an embodiment," or "an alternative embodiment" two or more times in different locations in this specification do not necessarily refer to the same embodiment. Furthermore, certain features, structures, or characteristics of one or more embodiments of this specification may be appropriately combined.

[0116] In addition, unless expressly stated in the claims, the order of the processing elements and sequences, the use of alphanumeric characters, or the use of other names described in this specification are not intended to limit the order of the processes and methods of this specification. Although the above disclosure discusses some currently considered useful utility model embodiments through various examples, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments. On the contrary, the claims are intended to cover all modifications and equivalent combinations that are consistent with the spirit and scope of the embodiments of this specification. For example, although the system components described above can be implemented by hardware devices, they can also be implemented only by software solutions, such as installing the described system on an existing server or mobile device.

[0117] Similarly, it should be noted that, in order to simplify the description of this specification and thus facilitate understanding of one or more embodiments of the utility model, the foregoing description of the embodiments of this specification sometimes combines multiple features into a single embodiment, figure, or description thereof. However, this disclosure method does not mean that the subject matter of this specification requires more features than those recited in the claims. In fact, the features of an embodiment may be fewer than all the features of the individual embodiments disclosed above.

[0118] In some embodiments, numbers are used to describe the quantity of components and attributes. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise stated, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the description and claims are approximate values, which may change according to the required characteristics of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of this specification are approximate values, in specific embodiments, the settings of such numerical values ​​are as accurate as possible within the feasible range.

[0119] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, and documents, cited in this specification is hereby incorporated by reference in its entirety. This includes application history documents that are inconsistent with or conflict with the content of this specification, as well as documents (currently or subsequently attached to this specification) that limit the broadest scope of the claims of this specification. It should be noted that if the descriptions, definitions, and / or terminology used in the accompanying materials are inconsistent or conflicting with the content of this specification, the descriptions, definitions, and / or terminology used in this specification will control.

[0120] Finally, it should be understood that the embodiments described in this specification are intended only to illustrate the principles of the embodiments of this specification. Other variations may also fall within the scope of this specification. Therefore, by way of example and not limitation, alternative configurations of the embodiments of this specification may be considered consistent with the teachings of this specification. Accordingly, the embodiments of this specification are not limited to the embodiments explicitly described and illustrated in this specification.

Claims

1. A speaker impedance measurement circuit, characterized in that: The circuit comprises: The first measuring circuit is used to measure the current value flowing through the speaker; the second measuring circuit is used to measure the voltage value across the speaker; an analog-to-digital conversion circuit, wherein a first input terminal of the analog-to-digital conversion circuit is connected to an output terminal of the first measurement circuit, and a second input terminal of the analog-to-digital conversion circuit is connected to an output terminal of the second measurement circuit, and is used to perform analog-to-digital conversion on the measured current value and the measured voltage value to obtain a current digital value and a voltage digital value and transmit them to a processor; A processor, wherein an input end of the processor is connected to an output end of the analog-to-digital conversion circuit, and the processor is used to calculate the impedance of the speaker according to the current digital quantity and the voltage digital quantity.

2. The circuit according to claim 1, characterized in that The first measurement circuit includes a sampling resistor and a sampling circuit. The sampling resistor is connected in series between the speaker and the power amplifier. The sampling circuit is used to sense the current flowing through the sampling resistor to obtain an output voltage. The output voltage is positively correlated with the current value. The input end of the second measurement circuit is connected between the sampling resistor and the speaker.

3. The circuit according to claim 2, characterized in that The sampling circuit comprises a differential amplifier for suppressing zero-point drift and interference in a differential input signal. A first input terminal and a second input terminal of the differential amplifier are respectively connected to two ends of a sampling resistor.

4. The circuit according to claim 3, characterized in that The sampling circuit also includes a first operational amplifier and a first low-pass filter. The operational amplifier is used to amplify the output signal of the differential amplifier. The non-inverting input terminal of the first operational amplifier is connected to the output terminal of the differential amplifier. The output terminal of the differential amplifier is connected to the non-inverting input terminal of the first operational amplifier through the first low-pass filter.

5. The circuit according to claim 4, characterized in that The second measurement circuit includes an attenuation circuit and a second operational amplifier. The attenuation circuit is used to reduce the strength of the signal input to the second measurement circuit. The input end of the attenuation circuit is connected between the sampling resistor and the speaker. The output end of the attenuation circuit is connected to the second operational amplifier. The second operational amplifier is used to reduce the strength of the signal input to the analog-to-digital conversion circuit.

6. The circuit according to claim 5, characterized in that The second measurement circuit further includes a feedback capacitor, the non-inverting input terminal of the second operational amplifier is connected to the ground, and the feedback capacitor is arranged between the inverting input terminal and the output terminal of the first operational amplifier.

7. The circuit according to claim 1, characterized in that The analog-to-digital conversion circuit includes an analog-to-digital conversion chip, the output end of the first measurement circuit is connected to the first input end of the analog-to-digital conversion chip through a second filter; the output end of the second measurement circuit is connected to the second input end of the analog-to-digital conversion chip through a third filter.

8. The circuit according to claim 7, characterized in that The interrupt pin, serial communication port and audio serial port of the analog-to-digital conversion chip are connected to the processor.

9. A speaker impedance measurement system, characterized in that: The system comprises a loudspeaker, a power amplifier, and a loudspeaker impedance measurement circuit according to any one of claims 1 to 8, wherein the loudspeaker impedance measurement circuit is arranged between an output end of the power amplifier and an input end of the loudspeaker.

10. The system according to claim 9, characterized in that The power amplifier comprises a first output end and a second output end. A first speaker impedance measurement circuit is arranged between the first output end and the input end of the first speaker. A second speaker impedance measurement circuit is arranged between the second output end and the input end of the second speaker.

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