Filter circuit, power amplifier device and loudspeaker

Abstract

The invention provides a filter circuit, a power amplifier device and a loudspeaker, and relates to the technical field of power amplifiers, the filter circuit comprises N filter units which are sequentially connected in series, and the output end of the nth filter unit is connected with the input end of the (n + 1) th filter unit; the bias current circuit is used for outputting a first current, and the output end of the bias current circuit is connected with the bias current ends of the N filter units; according to the filter unit, the output end of an operational amplifier circuit is the output end of the filter unit; the output end of the transconductance operational amplifier adjusting circuit is connected with the input end of the operational amplifier circuit, the bias current end of the transconductance operational amplifier adjusting circuit is connected with the output end of the bias current circuit, and the transconductance operational amplifier adjusting circuit is used for determining a corresponding frequency range according to the first current and is also used for transmitting a signal accessed from the input end of the transconductance operational amplifier adjusting circuit to the operational amplifier circuit; and filtering according to the frequency range and then outputting through the output end. According to the invention, the size can be effectively reduced, the adjustment process is simplified, and the filtering performance is improved.

Description

Technical Field

[0001] The present application relates to the technical field of power amplifiers, and in particular to a filter circuit, a power amplifier device and a loudspeaker. Background Art

[0002] The current design of advanced filters uses multi-gang potentiometers to adjust their cutoff frequency. However, this design method has its drawbacks. Due to the use of multi-gang potentiometers, the overall size of the filter is large, which is not conducive to product miniaturization and cost control. At the same time, the adjustment process is also cumbersome. Summary of the invention

[0003] The main purpose of the present invention is to provide a filter circuit, aiming to achieve product miniaturization of high-order filters and simplify the adjustment process.

[0004] To achieve the above object, the present invention provides a filter circuit, the filter circuit comprising: N filter units, the N filter units are connected in series in sequence, and the output end of the nth filter unit is connected to the input end of the n+1th filter unit; wherein N is a positive integer greater than or equal to 2, and n is a positive integer greater than or equal to 1 and less than N; A bias current circuit, the bias current circuit is used to output a first current, and an output end of the bias current circuit is respectively connected to the bias current ends of the N filter units; Wherein, the filter unit comprises: An operational amplifier circuit, wherein the output end of the operational amplifier circuit is the output end of the filter unit; A transconductance operational amplifier adjustment circuit, wherein the output end of the transconductance operational amplifier adjustment circuit is connected to the input end of the operational amplifier circuit, the bias current end of the transconductance operational amplifier adjustment circuit is connected to the output end of the bias current circuit, the input end of the transconductance operational amplifier adjustment circuit is the input end of the filter unit, and the transconductance operational amplifier adjustment circuit is used to determine the corresponding frequency range according to the first current, and is also used to filter the signal connected to its input end according to the frequency range and then output it through its output end.

[0005] Optionally, the transconductance amplifier adjustment circuit includes: a fifth resistor, wherein a first end of the fifth resistor is an input end of the transconductance operational amplifier adjustment circuit, and a second end of the fifth resistor is connected to the input end of the operational amplifier circuit; a transconductance operational amplifier circuit, wherein a signal input terminal of the transconductance operational amplifier circuit is connected to a first terminal of the fifth resistor, a bias current input terminal of the transconductance operational amplifier circuit is used to access a first current, and an output terminal of the transconductance operational amplifier circuit is connected to a second terminal of the fifth resistor; At least one capacitor, a first end of at least one of the capacitors is connected to the second end of the fifth resistor.

[0006] Optionally, the transconductance operational amplifier circuit includes: a first voltage-dividing circuit, wherein a first end of the first voltage-dividing circuit is connected to a first end of the fifth resistor, and a second end of the first voltage-dividing circuit is grounded; A transconductance amplifier chip, wherein a bias current input terminal of the transconductance amplifier chip is used to access a first current, a non-inverting terminal of the transconductance amplifier chip is connected to an output terminal of the first voltage divider circuit, and an output terminal of the transconductance amplifier chip is connected to a second terminal of the fifth resistor; A first resistor, wherein a first end of the first resistor is connected to an inverting end of the transconductance amplifier chip, and a second end of the first resistor is grounded.

[0007] Optionally, the first voltage divider circuit includes: a second resistor, wherein a first end of the second resistor is connected to a first end of the fifth resistor; a third resistor, a first end of the third resistor being connected to a second end of the second resistor, and a second end of the third resistor being grounded; Wherein, a common node of the second resistor and the third resistor is connected to the in-phase terminal of the transconductance amplifier chip.

[0008] Optionally, the filter unit further includes: A fourth resistor, wherein a first end of the fourth resistor is used to access the signal to be processed, and a second end of the fourth resistor is connected to the first end of the fifth resistor.

[0009] Optionally, the operational amplifier circuit includes: An operational amplifier chip, wherein the in-phase terminal of the operational amplifier chip is connected to the second end of the fifth resistor, the output terminal of the operational amplifier chip is connected to the inverting terminal, and the output terminal of the operational amplifier chip is the output terminal of the filter unit.

[0010] Optionally, the filter circuit further includes: An adjustable resistance circuit, wherein the input end of the adjustable resistance circuit is used to access the bias voltage, and the output end of the adjustable resistance circuit is connected to the input end of the bias current circuit.

[0011] Optionally, the adjustable resistance circuit includes: An adjustable potentiometer, wherein a first end of the adjustable potentiometer is used to access a bias voltage, and a second end of the adjustable potentiometer is connected to an input end of the bias current circuit.

[0012] In addition, to achieve the above-mentioned purpose, the present invention also provides a power amplifier device, which includes the filter circuit as described above.

[0013] In addition, to achieve the above-mentioned purpose, the present invention also provides a speaker, comprising the power amplifier device as described above.

[0014] The embodiment of the present invention is provided with N filter units connected in series, and the output end of the nth filter unit is connected to the input end of the n+1th filter unit, and the filter units are connected head to tail, and a bias current circuit is provided to output a first current to each filter unit. In addition, an operational amplifier circuit is provided in the filter unit, and the output end of the operational amplifier circuit is the output end of the filter unit, and a transconductance operational amplifier adjustment circuit is provided, and the output end of the transconductance operational amplifier adjustment circuit is connected to the input end of the operational amplifier circuit, and the bias current end of the transconductance operational amplifier adjustment circuit is connected to the output end of the bias current circuit, and the transconductance operational amplifier adjustment circuit is used to determine the corresponding frequency range according to the first current, and the signal connected to its input end is filtered according to the frequency range and output through its output end, thereby effectively reducing the volume, simplifying the adjustment process, and improving the filtering performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0017] Figure 1 is a circuit block diagram of a filter circuit according to an embodiment of the present invention; Figure 2 is a circuit block diagram of a filter circuit according to another embodiment of the present invention; Figure 3 for Figure 2 A circuit block diagram of a filter unit in; Figure 4 A circuit block diagram of a filter circuit according to another embodiment of the present invention; Figure 5 is a circuit block diagram of a filter circuit according to yet another embodiment of the present invention; Figure 6 4 is a circuit schematic diagram of the filter circuit of the present invention.

[0018] Description of Figure Numbers:

[0019] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, and well-known modules, units and their connections, links, communications or operations are not shown or described in detail. In addition, the described features, architectures or functions can be combined in any way in one or more embodiments. It should be understood by those skilled in the art that the various embodiments described below are only for illustration and are not intended to limit the scope of protection of the present invention.

[0021] The main solution of the embodiment of the present application is: by providing N filter units connected in series, and the output end of the nth filter unit is connected to the input end of the n+1th filter unit, the filter units are connected head to tail, and a bias current circuit is provided to output the first current to each filter unit. In addition, an operational amplifier circuit is provided in the filter unit, the output end of the operational amplifier circuit is the output end of the filter unit, and a transconductance operational amplifier adjustment circuit is provided, and the output end of the transconductance operational amplifier adjustment circuit is connected to the input end of the operational amplifier circuit, the bias current end of the transconductance operational amplifier adjustment circuit is connected to the output end of the bias current circuit, and the transconductance operational amplifier adjustment circuit is used to determine the corresponding frequency range according to the first current, and the signal connected to its input end is filtered according to the frequency range and then output through its output end.

[0022] The design of the advanced filter in the prior art uses a multi-potentiometer to adjust its cut-off frequency. However, this design method has defects. Due to the use of the multi-potentiometer, the overall size of the filter is large, which is not conducive to the miniaturization and cost control of the product, and the adjustment process is also cumbersome.

[0023] The present application provides a solution, which can effectively reduce the volume, simplify the adjustment process, and improve the filtering performance.

[0024] Reference Figure 1 In one embodiment of the present invention, the filter circuit includes N filter units 10 and a bias current circuit 20, wherein: N filter units 10 are connected in series in sequence, and the output end of the nth filter unit 10 is connected to the input end of the n+1th filter unit 10; wherein N is a positive integer greater than or equal to 2, and n is a positive integer greater than or equal to 1 and less than N; the bias current circuit 20 is used to output a first current, and the output end of the bias current circuit 20 is respectively connected to the bias current ends of the N filter units 10.

[0025] In the filter circuit, N filter units 10 are connected in series in sequence, for example, N is 5, that is, the filter unit 10 includes a first filter unit 10, a second filter unit 10, a third filter unit 10, a fourth filter unit 10 and a fifth filter unit 10, wherein the input end of the first filter unit 10 is connected to the signal to be processed, the output end of the first filter unit 10 is connected to the input end of the first filter unit 10, the output end of the second filter unit 10 is connected to the input end of the third filter unit 10, the output end of the third filter unit 10 is connected to the input end of the fourth filter unit 10, the output end of the fourth filter unit 10 is connected to the input end of the fifth filter unit 10, and the output end of the fifth filter unit 10 outputs the processed output signal, thereby forming a multi-order filter, wherein the filter units 10 of this embodiment are at least two. The bias current end of the first filter unit 10, the bias current end of the second filter unit 10, the bias current end of the third filter unit 10, the bias current end of the fourth filter unit 10 and the bias current end of the fifth filter unit 10 are respectively connected to the bias current circuit 20. The first filter unit 10, the second filter unit 10, the third filter unit 10, the fourth filter unit 10 and the fifth filter unit 10 can all determine the corresponding frequency range according to the first current output by the bias current circuit 20, and filter the connected signal to be processed according to the frequency range and output it through its output end.

[0026] Optionally, refer to Figure 2 and Figure 3 Another embodiment of the present invention provides a filter circuit based on the above Figure 1 In the illustrated embodiment, the filter unit 10 includes an operational amplifier circuit 11 and a transconductance operational amplifier adjustment circuit 12, wherein: The output end of the operational amplifier circuit 11 is the output end of the filter unit 10; the output end of the transconductance operational amplifier adjustment circuit 12 is connected to the input end of the operational amplifier circuit 11, the bias current end of the transconductance operational amplifier adjustment circuit 12 is connected to the output end of the bias current circuit 20, and the input end of the transconductance operational amplifier adjustment circuit 12 is the input end of the filter unit 10. The transconductance operational amplifier adjustment circuit 12 is used to determine the corresponding frequency range according to the first current, and is also used to filter the signal connected to its input end according to the frequency range and then output it through its output end.

[0027] In this embodiment, the operational amplifier circuit 11 can adopt a differential input and differential output configuration to improve the common mode rejection ratio of the circuit and the stability of signal processing. The transconductance operational amplifier adjustment circuit 12 changes the frequency response characteristics of the filter by adjusting the transconductance value, thereby enhancing or suppressing a specific frequency signal. In addition, the transconductance operational amplifier adjustment circuit 12 can also be dynamically adjusted through the first current to adapt to different filtering requirements.

[0028] Among them, a filter unit 10 is formed by a series combination of an operational amplifier circuit 11 and a transconductance operational amplifier adjustment circuit 12, which constitutes an order of the filter circuit, so that the filter circuit can achieve more refined frequency selection and wider frequency coverage. Moreover, due to the combination of the operational amplifier circuit 11 and the transconductance operational amplifier adjustment circuit 12, the use of multi-joint potentiometers can be effectively reduced, which not only improves the performance of the filter, but also simplifies the circuit design and reduces the cost. In addition, due to the dynamic adjustment ability of the transconductance operational amplifier adjustment circuit 12, the filter circuit can quickly adapt to changes in the signal environment and meet the needs of real-time signal processing. By adjusting the first current output by the bias current circuit 20, the frequency response characteristics of the filter unit 10 can be well optimized, thereby achieving the best filtering effect.

[0029] In this embodiment, an operational amplifier circuit 11 is provided in the filter unit 10, and the output end of the operational amplifier circuit 11 is the output end of the filter unit 10. A transconductance operational amplifier adjustment circuit 12 is further provided, and the output end of the transconductance operational amplifier adjustment circuit 12 is connected to the input end of the operational amplifier circuit 11, and the bias current end of the transconductance operational amplifier adjustment circuit 12 is connected to the output end of the bias current circuit 20. The transconductance operational amplifier adjustment circuit 12 is used to determine the corresponding frequency range according to the first current, and filter the signal connected to its input end according to the frequency range and then output it through its output end, thereby effectively reducing the volume, simplifying the adjustment process, and improving the filtering performance.

[0030] Optionally, refer to Figure 4 Another embodiment of the present invention provides a filter circuit based on the above Figure 2 and Figure 3 In any of the illustrated embodiments, the transconductance amplifier adjustment circuit 12 includes a fifth resistor R2, at least one capacitor, and a transconductance amplifier circuit 121, wherein: The first end of the fifth resistor R2 is the input end of the transconductance operational amplifier adjustment circuit, and the second end of the fifth resistor R2 is connected to the input end of the operational amplifier circuit; the signal input end of the transconductance operational amplifier circuit 121 is connected to the first end of the fifth resistor R2, the bias current input end of the transconductance operational amplifier circuit 121 is used to access the first current, and the output end of the transconductance operational amplifier circuit 121 is connected to the second end of the fifth resistor R2; the first end of at least one capacitor is connected to the second end of the fifth resistor R2.

[0031] In this embodiment, the transconductance amplifier circuit 121 adjusts its transconductance value according to the first current provided by the bias current circuit 20, thereby changing the frequency response characteristics of the filter. The two ends of the transconductance amplifier circuit 121 are connected in parallel with the fifth resistor R2. During the filtering process, the resistance value of the fifth resistor R2 can be changed, thereby playing an effect similar to that of a potentiometer. Its working process is similar to connecting a resistor in parallel on both sides of the fifth resistor R2, and the effect of the analog potentiometer is achieved by adjusting the current. Through this structural design, the filter circuit can achieve precise control of a specific frequency signal while maintaining the stability and reliability of the circuit.

[0032] By using the transconductance amplifier circuit 121, the use of multi-potentiometers can be effectively reduced, which not only improves the performance of the filter, but also simplifies the circuit design and reduces the cost. In addition, the dynamic adjustment capability of the transconductance amplifier circuit 121 enables the filter circuit to quickly adapt to changes in the signal environment and meet the needs of real-time signal processing. By adjusting the first current output by the bias current circuit 20, the frequency response characteristics of the filter unit 10 can be well optimized, thereby achieving the best filtering effect.

[0033] Optionally, refer to Figure 6 Another embodiment of the present invention provides a filter circuit based on the above Figure 4 In the embodiment shown, the transconductance amplifier circuit 121 includes a first voltage divider circuit 1211, a transconductance amplifier chip U2 and a first resistor R5, wherein: The first end of the first voltage divider circuit 1211 is connected to the first end of the fifth resistor R2, and the second end of the first voltage divider circuit 1211 is grounded; the bias current input end of the transconductance amplifier chip U2 is used to connect the first current, the in-phase end of the transconductance amplifier chip U2 is connected to the output end of the first voltage divider circuit 1211, and the output end of the transconductance amplifier chip U2 is connected to the second end of the fifth resistor R2; the first end of the first resistor R5 is connected to the inverting end of the transconductance amplifier chip U2, and the second end of the first resistor R5 is grounded.

[0034] In the present embodiment, the first voltage divider circuit 1211 is used to enable the transconductance amplifier chip U2 to better access the signal to be processed. As a core component, the bias current input terminal of the transconductance amplifier chip U2 receives the first current from the bias current circuit 20, and adjusts the transconductance value according to the current, thereby realizing the enhancement or suppression of the specific frequency signal. The in-phase terminal and the inverting terminal of the transconductance amplifier chip U2 are respectively connected to the output terminal of the first voltage divider circuit 1211 and the first resistor R5, and act together on the processing of the signal. The first resistor R5 is set to stabilize the inverting input terminal of the transconductance amplifier chip U2 to ensure the accuracy and stability of signal processing. The dynamic adjustment capability of the transconductance amplifier circuit 121 enables the filter circuit to quickly adapt to changes in the signal environment and meet the needs of real-time signal processing. By adjusting the first current output by the bias current circuit 20, the frequency response characteristics of the filter unit 10 can be well optimized, thereby achieving the best filtering effect.

[0035] Among them, the transconductance op amp chip U2 is compared with the ordinary op amp chip U1. The output of the ordinary op amp is a voltage signal, while the output of the transconductance op amp is a current signal, which makes it more directly used to control other circuit elements, such as transistors or capacitors, in some applications. Ordinary op amps generally use voltage feedback to stabilize gain and frequency response. Transconductance op amps can use current feedback, which allows designers to adjust the gain by changing external resistors, providing greater flexibility and being able to replace the original adjustable potentiometer VR. In addition, transconductance op amps tend to maintain better linearity under large signal conditions because their output current is directly related to the input voltage and is not affected by the power supply voltage. This means that when larger signals need to be processed, transconductance op amps may produce less distortion, while the linearity of ordinary op amps depends on the internal compensation network and other factors, and may have more nonlinear distortion under large signals.

[0036] Optionally, refer to Figure 6 Another embodiment of the present invention provides a filter circuit based on the above Figure 6 In the illustrated embodiment, the first voltage divider circuit 1211 includes a second resistor R3 and a third resistor R4, wherein: The first end of the second resistor R3 is connected to the first end of the fifth resistor R2; the first end of the third resistor R4 is connected to the second end of the second resistor R3, and the second end of the third resistor R4 is grounded; wherein the common node of the second resistor R3 and the third resistor R4 is connected to the in-phase end of the transconductance amplifier chip U2.

[0037] In this embodiment, by using a voltage divider network composed of the second resistor R3 and the third resistor R4, the input signal of the transconductance amplifier chip U2 can be well controlled. The resistance ratio of the second resistor R3 and the third resistor R4 can be designed as needed to achieve fine adjustment of the signal. The design of this voltage divider network not only improves the accuracy of signal processing, but also is easy to implement and adjust due to its simplicity.

[0038] This voltage divider circuit formed by the combination of the second resistor R3 and the third resistor R4 can ensure that the signal received by the transconductance amplifier chip U2 is within an appropriate voltage range, thereby ensuring stable operation of the circuit and optimizing the filtering effect.

[0039] Optionally, refer to Figure 6 Another embodiment of the present invention provides a filter circuit based on the above Figure 4 In the embodiment shown, the filter unit 10 further includes a fourth resistor R1, wherein: The first end of the fourth resistor R1 is used to access the signal to be processed, and the second end of the fourth resistor is connected to the first end of the fifth resistor R2.

[0040] In this embodiment, the signal to be processed is connected through the fourth resistor R1, and the fourth resistor R1 is used to set the upper limit of the cut-off frequency, thereby ensuring that the filter circuit can effectively filter out signal components higher than the set frequency. The series combination of the fourth resistor R1 and the fifth resistor R2 jointly determines the frequency response characteristics of the filter unit, so that the filter circuit can selectively amplify or attenuate signals within a specific frequency range according to actual application requirements, thereby ensuring the stable operation of the circuit and the optimization of the filtering effect. In addition, this design also allows the filter circuit to have better adaptability and reliability in different working environments.

[0041] Optionally, refer to Figure 6 Another embodiment of the present invention provides a filter circuit based on the above Figures 2 to 3 In any of the embodiments shown, the operational amplifier circuit 11 includes an operational amplifier chip U1, wherein: The in-phase terminal of the operational amplifier chip U1 is connected to the second end of the fifth resistor R2 , the output terminal of the operational amplifier chip U1 is connected to the inverting terminal, and the output terminal of the operational amplifier chip U1 is the output terminal of the filter unit 10 .

[0042] In this embodiment, an operational amplifier chip U1 is provided at the rear stage of the fifth resistor R2 to perform gain amplification or attenuation on the signal to be processed after filtering according to the frequency range. The in-phase end of the operational amplifier chip U1 receives the signal from the transconductance operational amplifier adjustment circuit 12, and its output end is directly connected to the inverting end to form a feedback loop. Among them, a resistor can also be connected in series between the output end and the inverting end of the operational amplifier chip U1 to better adjust the gain of the signal. This configuration allows the filter circuit to fine-tune the signal to meet specific filtering requirements. In addition, the output end of the operational amplifier chip U1, as the output end of the filter unit 10, can provide a stable output signal to ensure the stability and reliability of the filtering effect. Through this design, the filter circuit can effectively process various complex signals while maintaining good frequency selectivity and signal integrity.

[0043] Optionally, refer to Figure 5 Another embodiment of the present invention provides a filter circuit based on the above Figures 1 to 4 or Figure 6 In any of the illustrated embodiments, the filter circuit further comprises an adjustable resistance circuit 30, wherein: The input end of the adjustable resistance circuit 30 is used to access the bias voltage, and the output end of the adjustable resistance circuit 30 is connected to the input end of the bias current circuit 20 .

[0044] In the present embodiment, the adjustable resistor circuit 30 can provide flexible bias voltage adjustment to adapt to different circuit operating conditions. By changing the resistance value of the adjustable resistor, the input voltage of the bias current circuit 20 can be accurately controlled, thereby affecting the bias current of the transconductance amplifier chip U2. This design enables the filter circuit to be optimized according to actual application requirements to achieve optimal filtering performance. The introduction of the adjustable resistor circuit 30 not only enhances the adaptability of the circuit, but also provides convenience for the debugging and maintenance of the circuit. In addition, the use of the adjustable resistor circuit 30 can also reduce the dependence on fixed resistors, thereby reducing production costs and improving the scalability of the circuit.

[0045] The adjustable resistor circuit 30 may be a potentiometer, a digital potentiometer or other programmable resistor element. The potentiometer adjusts the resistance value through a mechanical knob or a sliding rod, while the digital potentiometer controls the change of the resistance value through a digital signal, thereby achieving more accurate and stable adjustment. In some applications, the adjustable resistor circuit 30 may also be automatically adjusted by a microcontroller to respond to changes in external conditions, ensuring that the filter circuit is always in the best working state.

[0046] Optionally, refer to Figure 6 Another embodiment of the present invention provides a filter circuit based on the above Figure 5 In the illustrated embodiment, the adjustable resistance circuit 30 includes an adjustable potentiometer VR, wherein: A first end of the adjustable potentiometer VR is used to access the bias voltage, and a second end of the adjustable potentiometer VR is connected to an input end of the bias current circuit 20 .

[0047] In this embodiment, the first end of the adjustable potentiometer VR is connected to the bias voltage source, and the second end is connected to the input end of the bias current circuit 20. The resistance of the adjustable potentiometer VR can be adjusted as needed to accurately control the input voltage of the bias current circuit 20, thereby affecting the bias current of the transconductance amplifier chip U2. This design enables the filter circuit to be optimized according to actual application requirements to achieve the best filtering performance. The introduction of the adjustable potentiometer VR enhances the adaptability of the circuit.

[0048] The present invention further provides a power amplifier device, which includes the filter circuit as described in the above embodiment.

[0049] It is worth noting that since the power amplifier device of the present invention is based on the above-mentioned filter circuit, the embodiments of the power amplifier device of the present invention include all technical solutions of all embodiments of the above-mentioned filter circuit, and the technical effects achieved are also exactly the same, which will not be repeated here.

[0050] The present invention further provides a loudspeaker, which includes the power amplifier device as described in the above embodiment.

[0051] It is worth noting that, since the loudspeaker of the present invention is based on the above-mentioned power amplifier device, the embodiments of the loudspeaker of the present invention include all technical solutions of all embodiments of the above-mentioned power amplifier device, and the technical effects achieved are also exactly the same, which will not be repeated here.

[0052] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A filter circuit, characterized in that: The filter circuit comprises: N filter units, the N filter units are connected in series in sequence, and the output end of the nth filter unit is connected to the input end of the n+1th filter unit; wherein N is a positive integer greater than or equal to 2, and n is a positive integer greater than or equal to 1 and less than N; A bias current circuit, the bias current circuit is used to output a first current, and an output end of the bias current circuit is respectively connected to the bias current ends of the N filter units; Wherein, the filter unit comprises: An operational amplifier circuit, wherein the output end of the operational amplifier circuit is the output end of the filter unit; A transconductance operational amplifier adjustment circuit, wherein the output end of the transconductance operational amplifier adjustment circuit is connected to the input end of the operational amplifier circuit, the bias current end of the transconductance operational amplifier adjustment circuit is connected to the output end of the bias current circuit, the input end of the transconductance operational amplifier adjustment circuit is the input end of the filter unit, and the transconductance operational amplifier adjustment circuit is used to determine the corresponding frequency range according to the first current, and is also used to filter the signal connected to its input end according to the frequency range and then output it through its output end.

2. The filter circuit according to claim 1, characterized in that The transconductance amplifier adjustment circuit comprises: a fifth resistor, wherein a first end of the fifth resistor is an input end of the transconductance operational amplifier adjustment circuit, and a second end of the fifth resistor is connected to the input end of the operational amplifier circuit; a transconductance operational amplifier circuit, wherein a signal input terminal of the transconductance operational amplifier circuit is connected to a first terminal of the fifth resistor, a bias current input terminal of the transconductance operational amplifier circuit is used to access a first current, and an output terminal of the transconductance operational amplifier circuit is connected to a second terminal of the fifth resistor; At least one capacitor, a first end of at least one of the capacitors is connected to the second end of the fifth resistor.

3. The filter circuit according to claim 2, characterized in that The transconductance operational amplifier circuit comprises: a first voltage-dividing circuit, wherein a first end of the first voltage-dividing circuit is connected to a first end of the fifth resistor, and a second end of the first voltage-dividing circuit is grounded; A transconductance amplifier chip, wherein a bias current input terminal of the transconductance amplifier chip is used to access a first current, a non-inverting terminal of the transconductance amplifier chip is connected to an output terminal of the first voltage divider circuit, and an output terminal of the transconductance amplifier chip is connected to a second terminal of the fifth resistor; A first resistor, wherein a first end of the first resistor is connected to an inverting end of the transconductance amplifier chip, and a second end of the first resistor is grounded.

4. The filter circuit according to claim 3, characterized in that The first voltage divider circuit comprises: a second resistor, wherein a first end of the second resistor is connected to a first end of the fifth resistor; a third resistor, a first end of the third resistor being connected to a second end of the second resistor, and a second end of the third resistor being grounded; Wherein, a common node of the second resistor and the third resistor is connected to the in-phase terminal of the transconductance amplifier chip.

5. The filter circuit according to claim 2, characterized in that The filter unit further comprises: A fourth resistor, wherein a first end of the fourth resistor is used to access the signal to be processed, and a second end of the fourth resistor is connected to the first end of the fifth resistor.

6. The filter circuit according to claim 1, wherein: The operational amplifier circuit comprises: An operational amplifier chip, wherein the in-phase terminal of the operational amplifier chip is connected to the second end of the fifth resistor, the output terminal of the operational amplifier chip is connected to the inverting terminal, and the output terminal of the operational amplifier chip is the output terminal of the filter unit.

7. The filter circuit according to any one of claims 1 to 6, characterized in that: The filter circuit further comprises: An adjustable resistance circuit, wherein the input end of the adjustable resistance circuit is used to access the bias voltage, and the output end of the adjustable resistance circuit is connected to the input end of the bias current circuit.

8. The filter circuit according to claim 7, characterized in that The adjustable resistance circuit comprises: An adjustable potentiometer, wherein a first end of the adjustable potentiometer is used to access a bias voltage, and a second end of the adjustable potentiometer is connected to an input end of the bias current circuit.

9. A power amplifier device, characterized in that: The power amplifier device comprises the filter circuit according to any one of claims 1 to 8.

10. A loudspeaker, characterized in that: Comprising the power amplifier device as claimed in claim 9.

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