WO2021128993A1

WO2021128993A1 - Amplifier circuit, and playing apparatus

Info

Publication number: WO2021128993A1
Application number: PCT/CN2020/116583
Authority: WO
Inventors: 宋益伟; 周涛
Original assignee: 锐迪科微电子（上海）有限公司
Priority date: 2019-12-25
Filing date: 2020-09-21
Publication date: 2021-07-01
Also published as: CN210518805U

Abstract

Provided are an amplifier circuit, and a playing apparatus. The amplifier circuit comprises filters to an N-th order, a comparator, and a digital circuit. After an original audio signal has passed through the filters, a filtered signal is obtained. After the filtered signal has passed through the comparator and the digital circuit, a corresponding digital signal is output. The number of operational amplifiers used in the filters is less than N. N is a natural number greater than 1. In the amplifier circuit of the present invention, reducing the number of operational amplifiers used in the filters to the Nth order reduces the area occupied by the circuit, and further reduces power consumption, without compromising filtering performance.

Description

Amplifying circuit and playback equipment

This application claims the priority of a Chinese patent application filed with the Chinese Patent Office, the application number is 201922370332.X, and the application name is "amplifier circuit and playback equipment" on December 25, 2019, the entire content of which is incorporated into this application by reference .

Technical field

The utility model relates to the technical field of integrated circuits, in particular to an amplifying circuit and a playback device.

Background technique

The existing amplifying circuit generally adopts two-stage filtering processing, in which the filter element adopts an operational amplifier, and then the filtered signal is converted into a digital signal through a comparator, and finally an audio signal is output by the player. The more the number of filters in the amplifying circuit, the higher the gain and the stronger the anti-interference ability of the circuit.

However, in an integrated circuit, the operational amplifier needs to occupy a larger circuit area, and there will be a relatively large power consumption.

Utility model content

The utility model provides an amplifying circuit and a playback device. On the premise of ensuring the filtering effect, the circuit area and power consumption of the amplifying circuit are reduced by reducing the number of operational amplifiers used in the N-order filter.

In the first aspect, an embodiment of the present invention also provides an amplifier circuit, including: an N-order filter, a comparator, and a digital circuit; the original audio signal passes through the N-order filter to obtain a filtered signal; the filtered signal passes through The comparator and the digital circuit output corresponding digital signals; wherein, the number of operational amplifiers used in the N-order filter is less than N, and N is a natural number greater than 1.

In a possible design, the N-th order filter includes an i-1th order filter and an i-th order filter, where the value range of i is 2, 3,..., N;

The i-1th order filter is a first-order filter, and the first-order filter includes: an operational amplifier, a first capacitor, and a second capacitor; the positive input terminal of the operational amplifier is connected to the previous first-order filter The positive output terminal of the operational amplifier, the negative input terminal of the operational amplifier is connected to the negative output terminal of the previous-order filter, the first output terminal of the operational amplifier constitutes the first output terminal of the filter, and the first One end of the capacitor is connected to the positive input terminal of the operational amplifier, the other end of the first capacitor is connected to the negative output terminal of the operational amplifier; one end of the second capacitor is connected to the negative input terminal of the operational amplifier , The other end of the second capacitor is connected to the positive output end of the operational amplifier;

The i-th order filter is a second type filter, and the second type filter includes: a third capacitor, a first resistor, a fourth capacitor, and a second resistor;

One end of the third capacitor is connected to the positive input end of the i-1th order filter, the other end of the third capacitor is connected to one end of the first resistor, and the other end of the first resistor is connected to the The positive output terminal of the operational amplifier;

One end of the fourth capacitor is connected to the negative input end of the i-1th order filter, the other end of the fourth capacitor is connected to one end of the second resistor, and the other end of the second resistor is connected to the The negative output terminal of the operational amplifier.

The i-th order filter is a second type filter, and the second type filter includes: a third capacitor, a first switched capacitor, a fourth capacitor, and a second switched capacitor;

One end of the third capacitor is connected to the positive input end of the i-1th order filter, the other end of the third capacitor is connected to one end of the first switched capacitor, and the other end of the first switched capacitor is connected to The positive output terminal of the operational amplifier;

One end of the fourth capacitor is connected to the negative input end of the i-1th order filter, the other end of the fourth capacitor is connected to one end of the second switched capacitor, and the other end of the second switched capacitor is connected to The negative output terminal of the operational amplifier.

In a possible design, the capacitance values of the third capacitor and the fourth capacitor in the i-1th order filter, and the first capacitor and the second capacitor of the i-1th order filter All the same.

In a possible design, if the i-1th order filter is a first type filter and the i-th order filter is a first type filter, the circuit further includes: a third resistor And the fourth resistor;

The positive output terminal of the operational amplifier in the i-1th order filter is connected to the positive input terminal of the operational amplifier in the i-th order filter through the third resistor;

The negative output terminal of the operational amplifier in the i-1th order filter is connected to the negative input terminal of the operational amplifier in the i-th order filter through the fourth resistor.

In a possible design, it further includes: a fifth capacitor and a sixth capacitor;

One end of the fifth capacitor is connected to the positive output end of the operational amplifier in the i-1th order filter, and the other end of the fifth capacitor is connected to the positive input of the operational amplifier in the i-th order filter end;

One end of the sixth capacitor is connected to the negative output terminal of the operational amplifier in the i-1th order filter, and the other end of the sixth capacitor is connected to the negative input terminal of the operational amplifier in the i-th order filter end.

In a possible design, it further includes: a weighted adder, the original audio signal is divided into two, the first original audio signal passes through the N-order filter to obtain a filtered signal; the second original audio signal The signal is weighted and added to the filtered signal by the weighted adder to obtain a weighted added signal, and the weighted added signal passes through the comparator and the digital circuit to output a corresponding digital signal.

In a possible design, the weighted adder includes: a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor;

One end of the fifth resistor is connected to the first output end of the last-order filter, one end of the sixth resistor is connected to the positive output end of the second original audio signal; the other end of the fifth resistor is connected to the first output end of the first-order filter. The other ends of the six resistors are all connected to the first input end of the integrated circuit composed of the comparator and the digital circuit;

One end of the seventh resistor is connected to the second output end of the last-order filter, one end of the eighth resistor is connected to the negative output end of the second original audio signal; the other end of the seventh resistor is connected to the first The other ends of the eight resistors are all connected to the second input end of the integrated circuit composed of the comparator and the digital circuit.

In a possible design, the weighted adder includes: a third switched capacitor, a fourth switched capacitor, a fifth switched capacitor, and a sixth switched capacitor;

One end of the third switched capacitor is connected to the first output end of the last-order filter, one end of the fourth switched capacitor is connected to the positive output end of the second original audio signal; the other end of the third switched capacitor is connected to The other end of the fourth switched capacitor is connected to the first input end of the integrated circuit composed of the comparator and the digital circuit;

One end of the fifth switched capacitor is connected to the second output end of the last-order filter, one end of the sixth switched capacitor is connected to the negative output end of the second original audio signal; the other end of the fifth switched capacitor is connected to The other end of the sixth switched capacitor is connected to the second input end of the integrated circuit composed of the comparator and the digital circuit.

In the second aspect, an embodiment of the present invention also provides a playback device, including the amplifying circuit as described in any one of the first aspect.

The amplifying circuit and playback device provided by the utility model obtain a filtered signal after passing the original audio signal through the N-order filter; the filtered signal outputs the corresponding digital signal after passing through the comparator and the digital circuit; wherein , The number of operational amplifiers used in the N-order filter is less than N, and N is a natural number greater than 1. Under the premise of ensuring the filtering effect, the amplifier circuit of the utility model reduces the circuit area and power consumption of the amplifier circuit by reducing the number of operational amplifiers used in the N-order filter.

Description of the drawings

In order to more clearly explain the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the appendix in the following description The drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor.

FIG. 1 is a schematic diagram of the structure of the amplifying circuit provided by the first embodiment of the utility model;

2 is a schematic diagram of the structure of the amplifying circuit provided by the second embodiment of the utility model;

3 is a schematic diagram of the structure of the amplifying circuit provided by the third embodiment of the utility model;

4 is a schematic diagram of the structure of the amplifying circuit provided by the fourth embodiment of the present invention.

Through the above drawings, the specific embodiments of the present disclosure have been shown, which will be described in more detail below. These drawings and text description are not intended to limit the scope of the concept of the present disclosure in any way, but to explain the concept of the present disclosure for those skilled in the art by referring to specific embodiments.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be described clearly and completely in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the description The embodiments are part of the embodiments of the present utility model, but not all of the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the scope of protection of the present utility model.

The terms "first", "second", "third", "fourth", etc. (if any) in the description and claims of the present utility model and the above-mentioned drawings are used to distinguish similar objects without having to use To describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described herein can be implemented in a sequence other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any variations of them are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those clearly listed. Those steps or units may include other steps or units that are not clearly listed or are inherent to these processes, methods, products, or equipment.

The technical solution of the present utility model will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.

The existing amplifying circuit generally adopts two-stage filtering processing, in which the filter element adopts an operational amplifier, and then the filtered signal is converted into a digital signal through a comparator and a digital circuit, and finally an audio signal is output by the player. The more the number of filters in the amplifying circuit, the higher the gain and the stronger the anti-interference ability of the circuit.

However, in an integrated circuit, the operational amplifier needs to occupy a larger circuit area and will increase the power consumption of the amplifying circuit.

In view of the above problems, the present invention aims to improve an amplifying circuit. Under the premise of ensuring the filtering effect, the number of operational amplifiers used in the N-order filter is reduced to reduce the circuit area and power consumption of the amplifying circuit.

Hereinafter, specific embodiments are used to describe in detail the technical solution of the present invention and how the technical solution of the present application solves the above-mentioned technical problems. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present invention will be described below in conjunction with the accompanying drawings.

Example one

Figure 1 is a schematic diagram of the structure of the amplifying circuit provided in the first embodiment of the utility model. As shown in Figure 1, the amplifying circuit in this embodiment may include: an N-order filter, a comparator, and a digital circuit; the original audio signal passes through the N-order After the filter, a filtered signal is obtained; the filtered signal passes through an integrated circuit composed of a comparator and a digital circuit and outputs a corresponding digital signal; wherein, the number of operational amplifiers used in the N-order filter is less than N, and N is a natural number greater than 1.

Specifically, referring to Figure 1, the positive input of the first-order filter receives the positive signal Vip of the first audio signal, and the negative input of the first-order filter receives the negative signal Vin of the first audio signal. The reference terminal of the filter receives the reference signal Vcom. The positive output terminal of the previous-order filter is connected to the positive input terminal of the latter-order filter, and the negative output terminal of the previous-order filter is connected to the negative input terminal of the latter-order filter. The positive output terminal and the negative output terminal of the last-order filter are connected to the input terminal of the integrated circuit composed of the comparator and the digital circuit, and the output terminal of the integrated circuit composed of the comparator and the digital circuit is connected to the player.

Under the premise of ensuring the filtering effect, the amplifier circuit of this embodiment reduces the circuit area and power consumption of the amplifier circuit by reducing the number of operational amplifiers used in the N-order filter.

Example two

Figure 2 is a schematic structural diagram of the amplifying circuit provided in the second embodiment of the utility model. As shown in Figure 2, the amplifying circuit in this embodiment may include: an integrated circuit composed of an N-order filter, a comparator, and a digital circuit; After the signal passes through an N-order filter, a filtered signal is obtained; the filtered signal passes through an integrated circuit composed of a comparator and a digital circuit and outputs the corresponding digital signal; among them, the number of operational amplifiers used in the N-order filter is less than N, and N is greater than The natural number of 1.

In an optional implementation manner, referring to FIG. 2, the N-th order filter includes an i-1th order filter and an i-th order filter, where the value range of i is 2, 3,...,N. The i-1th order filter is the first type filter, the first type filter includes: operational amplifier, first capacitor, second capacitor; the positive input terminal of the operational amplifier is connected to the positive output terminal of the previous first-order filter, The negative input terminal of the operational amplifier is connected to the negative output terminal of the previous first-order filter, the first output terminal of the operational amplifier constitutes the first output terminal of the filter, and one end of the first capacitor is connected to the positive input terminal of the operational amplifier. The other end of the capacitor is connected to the negative output end of the operational amplifier; one end of the second capacitor is connected to the negative input end of the operational amplifier, and the other end of the second capacitor is connected to the positive output end of the operational amplifier. The i-th order filter is the second type filter. The second type filter includes: a third capacitor, a first resistor, a fourth capacitor, and a second resistor; one end of the third capacitor is connected to the i-1 order filter Positive input, the other end of the third capacitor is connected to one end of the first resistor, and the other end of the first resistor is connected to the positive output end of the operational amplifier; one end of the fourth capacitor is connected to the negative input end of the i-1th order filter , The other end of the fourth capacitor is connected to one end of the second resistor, and the other end of the second resistor is connected to the negative output end of the operational amplifier.

In another optional implementation manner, the N-th order filter includes an i-1th order filter and an i-th order filter, where the value range of i is 2, 3,...,N. The i-1th order filter is the first type filter, the first type filter includes: operational amplifier, first capacitor, second capacitor; the positive input terminal of the operational amplifier is connected to the positive output terminal of the previous first-order filter, The negative input terminal of the operational amplifier is connected to the negative output terminal of the previous first-order filter, the first output terminal of the operational amplifier constitutes the first output terminal of the filter, and one end of the first capacitor is connected to the positive input terminal of the operational amplifier. The other end of the capacitor is connected to the negative output end of the operational amplifier; one end of the second capacitor is connected to the negative input end of the operational amplifier, and the other end of the second capacitor is connected to the positive output end of the operational amplifier. The i-th order filter is a second type filter, and the second type filter includes: a third capacitor, a first switched capacitor, a fourth capacitor, and a second switched capacitor. One end of the third capacitor is connected to the positive input end of the i-1th order filter, the other end of the third capacitor is connected to one end of the first switched capacitor, and the other end of the first switched capacitor is connected to the positive output end of the operational amplifier. One end of the fourth capacitor is connected to the negative input end of the i-1th order filter, the other end of the fourth capacitor is connected to one end of the second switched capacitor, and the other end of the second switched capacitor is connected to the negative output end of the operational amplifier.

It should be noted that this embodiment does not limit the number of filters.

It should be noted that the capacitance values of the third capacitor and the fourth capacitor in the i-th order filter and the first capacitor and the second capacitor of the i-1th order filter in this embodiment are the same.

The amplifying circuit of this embodiment obtains a filtered signal after passing the original audio signal through an N-order filter; the filtered signal outputs a corresponding digital signal after passing through a comparator and a digital circuit; among them, the operational amplifier used in the N-order filter The number of is less than N, and N is a natural number greater than 1. Under the premise of ensuring the filtering effect, the amplifier circuit of the utility model reduces the circuit area and power consumption of the amplifier circuit by reducing the number of operational amplifiers used in the N-order filter.

Example three

Figure 3 is a schematic diagram of the structure of the amplifying circuit provided in the third embodiment of the utility model. As shown in Figure 3, the amplifying circuit in this embodiment may include: an N-order filter, a comparator, and a digital circuit; the original audio signal passes through the N-order After the filter, a filtered signal is obtained; the filtered signal passes through an integrated circuit composed of a comparator and a digital circuit and outputs a corresponding digital signal; wherein, the number of operational amplifiers used in the N-order filter is less than N, and N is a natural number greater than 1.

Refer to Figure 3 for a detailed description with a third-order filter as an example. The first-order filter includes: a first operational amplifier INT1 and two capacitors, the positive input terminal of the first operational amplifier INT1 is connected to the positive output terminal of the first operational amplifier INT1 through a capacitor, and the negative input terminal of the first operational amplifier INT1 It is connected to the negative output terminal of the first operational amplifier INT1 through a capacitor. The positive input terminal of the first operational amplifier INT1 constitutes the positive input terminal of the first-order filter, the negative input terminal of the first operational amplifier INT1 constitutes the negative input terminal of the first-order filter, and the positive output terminal of the first operational amplifier INT1 The positive output terminal of the first-order filter is formed, and the negative output terminal of the first operational amplifier INT1 is the negative output terminal of the first-order filter. The second-order filter includes: a second operational amplifier INT2, a first capacitor C1, and a second capacitor C2; the positive input end of the second operational amplifier INT2 is connected to the positive output end of the previous first-order filter, and the second operational amplifier INT2 The negative input terminal is connected to the negative output terminal of the first-order filter, the positive output terminal of the second operational amplifier INT2 constitutes the positive output terminal of the second-order filter, and one end of the first capacitor C1 is connected to the positive output terminal of the second operational amplifier INT2. At the input end, the other end of the first capacitor C1 is connected to the negative output end of the second operational amplifier INT2; one end of the second capacitor C1 is connected to the negative input end of the second operational amplifier INT2, and the other end of the second capacitor C2 is connected to the first The positive output terminal of the second amplifier INT2 and the positive output terminal of the second amplifier INT2 constitute the negative output terminal of the second-order filter. The third-order filter includes: a third capacitor C3, a first resistor R1, a fourth capacitor C4, and a second resistor R2; one end of the third capacitor C3 is connected to the positive input terminal of the second operational amplifier INT2, and the third capacitor C3 The other end is connected to one end of the first resistor R1, the other end of the first resistor R1 is connected to the positive output end of the second operational amplifier INT2; one end of the fourth capacitor C4 is connected to the negative input end of the second operational amplifier INT2, and the fourth capacitor The other end of C4 is connected to one end of the second resistor R2, and the other end of the second resistor R2 is connected to the negative output end of the second operational amplifier INT2.

In an optional implementation manner, if the i-1th order filter is a first type filter and the i-th order filter is a first type filter, the circuit further includes: a third resistor and a fourth resistor ; The positive output terminal of the operational amplifier in the i-1th order filter is connected to the positive input terminal of the operational amplifier in the i-th order filter through a third resistor; the negative output terminal of the operational amplifier in the i-1th order filter It is connected to the negative input terminal of the operational amplifier in the i-th order filter through the fourth resistor.

In another optional implementation manner, if the i-1th order filter is a first type filter and the i-th order filter is a first type filter, the circuit further includes: a fifth capacitor and a sixth capacitor ; One end of the fifth capacitor is connected to the positive output end of the operational amplifier in the i-1th order filter, and the other end of the fifth capacitor is connected to the positive input end of the operational amplifier in the i-th order filter; one end of the sixth capacitor It is connected to the negative output terminal of the operational amplifier in the i-1th order filter, and the other end of the sixth capacitor is connected to the negative input terminal of the operational amplifier in the i-th order filter.

Refer to Figure 3 for a detailed description with a third-order filter as an example. If the first-order filter is the first-class filter and the second-order filter is the first-class filter, the circuit further includes: a third resistor R3, a fourth resistor R4, a fifth capacitor C5, and a sixth capacitor C6 ; The positive output terminal of the operational amplifier in the first-order filter is connected to the positive input terminal of the operational amplifier in the second-order filter through the third resistor R3; the negative output terminal of the operational amplifier in the first-order filter passes through the fourth The resistor R4 is connected to the negative input terminal of the operational amplifier in the second-order filter. One end of the fifth capacitor C5 is connected to the positive output end of the operational amplifier in the first-order filter, the other end of the fifth capacitor C5 is connected to the positive input end of the operational amplifier in the second-order filter; one end of the sixth capacitor C6 It is connected to the negative output terminal of the operational amplifier in the first-order filter, and the other end of the sixth capacitor C6 is connected to the negative input terminal of the operational amplifier in the second-order filter.

Example four

Fig. 4 is a schematic structural diagram of the amplifying circuit provided in the fourth embodiment of the utility model. As shown in Fig. 4, the amplifying circuit in this embodiment may include: an N-order filter, a weighted adder, a comparator, and a digital circuit; After the original audio signal passes through the N-order filter, the filtered signal is obtained; the second original audio signal is weighted and added with the filtered signal through a weighted adder to obtain a weighted added signal; the weighted added signal passes through a comparator, a digital circuit, and The player outputs audio signals. The filtered signal outputs the corresponding digital signal after passing through the comparator and digital circuit; among them, the number of operational amplifiers used in the N-order filter is less than N, and N is a natural number greater than 1.

The positive output terminal of the last-order filter is connected to the first input port of the first weighted adder, and the negative output terminal of the last-order filter is connected to the first input port of the second weighted adder. The second input port of the first weighted adder receives the positive signal Vip of the second audio signal, and the second input port of the second weighted adder receives the negative signal Vin of the second audio signal. The output terminal of the first weighted adder is connected to the first input terminal of the integrated circuit formed by the comparator and the digital circuit, and the output terminal of the second weighted adder is connected to the second input terminal of the integrated circuit formed by the comparator and the digital circuit. The output terminal of the integrated circuit composed of the comparator and the digital circuit is connected with the player.

It should be noted that this embodiment does not limit the number of filters in the circuit.

In an optional embodiment, the weighted adder includes: a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor; one end of the fifth resistor is connected to the first output end of the last-order filter, and the sixth One end of the resistor is connected to the positive output end of the second original audio signal; the other end of the fifth resistor and the other end of the sixth resistor are both connected to the first input end of the integrated circuit composed of a comparator and a digital circuit; One end is connected to the second output end of the last-order filter, one end of the eighth resistor is connected to the negative output end of the second original audio signal; the other end of the seventh resistor and the other end of the eighth resistor are both connected to the comparator and digital The second input terminal of the integrated circuit composed of the circuit.

It should be noted that this embodiment does not limit the resistance values of the fifth resistor, the sixth resistor, the seventh resistor, and the eighth resistor. Those skilled in the art can adjust the weighted addition ratio of the two audio signals by setting the resistance values of the fifth resistor, the sixth resistor, the seventh resistor, and the eighth resistor.

In another alternative embodiment, the weighted adder includes: a third switched capacitor, a fourth switched capacitor, a fifth switched capacitor, and a sixth switched capacitor; one end of the third switched capacitor is connected to the first-order filter of the last-order filter. One output end, one end of the fourth switched capacitor is connected to the positive output end of the second original audio signal; the other end of the third switched capacitor and the other end of the fourth switched capacitor are both connected to the integrated circuit composed of the comparator and the digital circuit The first input terminal; one end of the fifth switched capacitor is connected to the second output terminal of the last-order filter, one end of the sixth switched capacitor is connected to the negative output terminal of the second original audio signal; the other end of the fifth switched capacitor is connected to the first The other ends of the six switched capacitors are all connected to the second input end of the integrated circuit composed of the comparator and the digital circuit.

In this embodiment, the original audio signal is divided into two channels. One original audio signal passes through an N-order filter to obtain a filtered signal; the other original audio signal is weighted and added to the filtered signal through a weighted adder to obtain a weighted addition signal ; The weighted sum signal passes through the comparator, the digital circuit, and the player in sequence to output an audio signal. Therefore, the original audio signal of another channel can be used to improve the linearity of the filtered signal, and the quality of the output audio signal can be improved by performing feedforward processing on the signal entering the comparator and the digital circuit.

In addition, the present invention also provides a playback device, and the playback device is provided with an amplifying circuit as shown in any one of FIGS. 1 to 4.

In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner" The orientation or positional relationship of indications such as "outside" is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific The orientation, structure and operation in a specific orientation, therefore cannot be understood as a limitation of the present utility model. In the description of the present invention, "multiple" means two or more than two, unless it is specifically specified otherwise.

The terms "first", "second", "third", "fourth", etc. (if any) in the description and claims of this application and the above-mentioned drawings are used to distinguish similar objects, without having to use To describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in a sequence other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any variations of them are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those clearly listed. Those steps or units may include other steps or units that are not clearly listed or are inherent to these processes, methods, products, or equipment.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the utility model, not to limit it; although the utility model has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand ：It is still possible to modify the technical solutions recorded in the foregoing embodiments, or equivalently replace some or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the embodiments of the utility model. The scope of the technical solution.

Claims

An amplifying circuit, characterized by comprising: an N-order filter, a comparator, and a digital circuit; the original audio signal passes through the N-order filter to obtain a filtered signal; the filtered signal passes through the comparator, the The digital circuit outputs a corresponding digital signal; wherein, the number of operational amplifiers used in the N-order filter is less than N, and N is a natural number greater than 1.
The circuit according to claim 1, wherein the N-th order filter includes an i-1th order filter and an i-th order filter, wherein the value range of i is 2, 3,..., N ；

The i-1th order filter is a first-order filter, and the first-order filter includes: an operational amplifier, a first capacitor, and a second capacitor; the positive input terminal of the operational amplifier is connected to the previous first-order filter The positive output terminal of the operational amplifier, the negative input terminal of the operational amplifier is connected to the negative output terminal of the previous-order filter, the first output terminal of the operational amplifier constitutes the first output terminal of the filter, and the first One end of the capacitor is connected to the positive input terminal of the operational amplifier, the other end of the first capacitor is connected to the negative output terminal of the operational amplifier; one end of the second capacitor is connected to the negative input terminal of the operational amplifier , The other end of the second capacitor is connected to the positive output end of the operational amplifier;

The i-th order filter is a second type filter, and the second type filter includes: a third capacitor, a first resistor, a fourth capacitor, and a second resistor;

One end of the third capacitor is connected to the positive input end of the i-1th order filter, the other end of the third capacitor is connected to one end of the first resistor, and the other end of the first resistor is connected to the The positive output terminal of the operational amplifier;

One end of the fourth capacitor is connected to the negative input end of the i-1th order filter, the other end of the fourth capacitor is connected to one end of the second resistor, and the other end of the second resistor is connected to the The negative output terminal of the operational amplifier.
The circuit according to claim 1, wherein the N-th order filter includes an i-1th order filter and an i-th order filter, wherein the value range of i is 2, 3,..., N ；

The i-1th order filter is a first-order filter, and the first-order filter includes: an operational amplifier, a first capacitor, and a second capacitor; the positive input terminal of the operational amplifier is connected to the previous first-order filter The positive output terminal of the operational amplifier, the negative input terminal of the operational amplifier is connected to the negative output terminal of the previous-order filter, the first output terminal of the operational amplifier constitutes the first output terminal of the filter, and the first One end of the capacitor is connected to the positive input terminal of the operational amplifier, the other end of the first capacitor is connected to the negative output terminal of the operational amplifier; one end of the second capacitor is connected to the negative input terminal of the operational amplifier , The other end of the second capacitor is connected to the positive output end of the operational amplifier;

The i-th order filter is a second type filter, and the second type filter includes: a third capacitor, a first switched capacitor, a fourth capacitor, and a second switched capacitor;

One end of the third capacitor is connected to the positive input end of the i-1th order filter, the other end of the third capacitor is connected to one end of the first switched capacitor, and the other end of the first switched capacitor is connected to The positive output terminal of the operational amplifier;

One end of the fourth capacitor is connected to the negative input end of the i-1th order filter, the other end of the fourth capacitor is connected to one end of the second switched capacitor, and the other end of the second switched capacitor is connected to The negative output terminal of the operational amplifier.
The circuit according to claim 2 or 3, wherein the third capacitor and the fourth capacitor in the i-th order filter, and the first capacitor and the fourth capacitor in the i-1th order filter The capacitance values of the two capacitors are the same.
The circuit according to claim 2 or 3, wherein if the i-1th order filter is a first type filter and the i-th order filter is a first type filter, then the The circuit also includes: a third resistor and a fourth resistor;

The positive output terminal of the operational amplifier in the i-1th order filter is connected to the positive input terminal of the operational amplifier in the i-th order filter through the third resistor;

The negative output terminal of the operational amplifier in the i-1th order filter is connected to the negative input terminal of the operational amplifier in the i-th order filter through the fourth resistor.
The circuit of claim 5, further comprising: a fifth capacitor and a sixth capacitor;

One end of the fifth capacitor is connected to the positive output end of the operational amplifier in the i-1th order filter, and the other end of the fifth capacitor is connected to the positive input end of the operational amplifier in the i-th order filter end;

One end of the sixth capacitor is connected to the negative output terminal of the operational amplifier in the i-1th order filter, and the other end of the sixth capacitor is connected to the negative input terminal of the operational amplifier in the i-th order filter end.
The circuit according to claim 1, further comprising: a weighted adder, the original audio signal is divided into two paths, the first original audio signal passes through the N-order filter to obtain a filtered signal; The second original audio signal is weighted and added to the filtered signal by the weighted adder to obtain a weighted added signal, and the weighted added signal passes through the comparator and the digital circuit to output a corresponding digital signal.
The circuit according to claim 7, wherein the weighted adder comprises: a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor;

One end of the fifth resistor is connected to the first output end of the last-order filter, one end of the sixth resistor is connected to the positive output end of the second original audio signal; the other end of the fifth resistor is connected to the first output end of the first-order filter. The other ends of the six resistors are all connected to the first input end of the integrated circuit composed of the comparator and the digital circuit;

One end of the seventh resistor is connected to the second output end of the last-order filter, one end of the eighth resistor is connected to the negative output end of the second original audio signal; the other end of the seventh resistor is connected to the first The other ends of the eight resistors are all connected to the second input end of the integrated circuit composed of the comparator and the digital circuit.
8. The circuit of claim 7, wherein the weighted adder comprises: a third switched capacitor, a fourth switched capacitor, a fifth switched capacitor, and a sixth switched capacitor;

One end of the third switched capacitor is connected to the first output end of the last-order filter, one end of the fourth switched capacitor is connected to the positive output end of the second original audio signal; the other end of the third switched capacitor is connected to The other end of the fourth switched capacitor is connected to the first input end of the integrated circuit composed of the comparator and the digital circuit;

One end of the fifth switched capacitor is connected to the second output end of the last-order filter, one end of the sixth switched capacitor is connected to the negative output end of the second original audio signal; the other end of the fifth switched capacitor is connected to The other end of the sixth switched capacitor is connected to the second input end of the integrated circuit composed of the comparator and the digital circuit.
A playback device, characterized by comprising the amplifying circuit according to any one of claims 1-9.