WO2020135308A1

WO2020135308A1 - High-voltage digital audio power amplification system

Info

Publication number: WO2020135308A1
Application number: PCT/CN2019/127315
Authority: WO
Inventors: 周佳宁; 张海军
Original assignee: 上海艾为电子技术股份有限公司
Priority date: 2018-12-26
Filing date: 2019-12-23
Publication date: 2020-07-02

Abstract

Provided by the present invention is a high-voltage digital audio power amplification system, wherein the high-voltage digital audio power amplification system increases the output power of the high-voltage digital audio power amplification system by means of providing a current source generation module, which is used for providing a power supply for a first sub-system and a second sub-system such that the high-voltage digital audio power amplification system operates within a high voltage range.

Description

High-voltage digital audio power amplifier system

This application requires a Chinese patent application submitted to the Chinese Patent Office on December 26, 2018, with the application number CN201811597824.6, and the invention titled "a high-voltage digital audio power amplifier system", and submitted to the Chinese Patent Office on December 26, 2018 The priority of the Chinese patent application with the application number CN201811597843.9 and the invention titled "A high-voltage digital audio power amplifier system", the entire contents of which are incorporated by reference in this application.

Technical field

The invention relates to the technical field of semiconductor integrated circuits, and more particularly, to a high-voltage digital audio power amplifier system.

Background technique

At present, Class D audio power amplifiers are widely used due to their efficiency of more than 80%. Especially high efficiency is essential for mobile devices, which can not only extend working hours, but also reduce the calorific value of mobile phones and other handheld devices.

In applications such as mobile phones, volume and sound quality have an important impact on the user experience. The current trend is that audio amplifiers output higher power to obtain greater volume and better sound quality.

However, the current digital audio power amplifier system cannot achieve high voltage output.

Summary of the invention

In view of this, the present invention provides a high-voltage digital audio power amplifier system to solve the problem that high-voltage output cannot be realized in the prior art.

To achieve the above objectives, the present invention provides the following technical solutions:

A high-voltage digital audio power amplifier system includes: a first subsystem, a second subsystem, a first feedback module, a second feedback module, and a current source generating module;

The first subsystem includes: a first current source module and a first power amplifier loop, the output end of the first current source module is connected to the first input end of the first power amplifier loop, the first current The input terminal of the source module is used as the signal input terminal of the first subsystem to receive the PWMP signal, and the output terminal of the first power amplifier loop is used as the output terminal of the first subsystem;

The second subsystem includes: a second current source module and a second power amplifier loop, the output end of the second current source module is connected to the first input end of the second power amplifier loop, the second current The input terminal of the source module is used as the signal input terminal of the second subsystem to receive the PWMN signal, and the output terminal of the second power amplifier loop is used as the output terminal of the second subsystem;

One end of the first feedback module is connected to the first input end of the first power amplifier loop, and the other end is connected to the output end of the first power amplifier loop;

One end of the second feedback module is connected to the first input end of the second power amplifier loop, and the other end is connected to the output end of the second power amplifier loop;

The first end of the current source generating module is connected to the first input end of the first power amplifier loop, the second end is connected to the first input end of the second power amplifier loop, and the third end is connected to the power supply Terminal, the fourth terminal is connected to the voltage input terminal, and the fifth terminal is connected to ground;

Wherein, the current source generating module is used to provide current for the first subsystem and the second subsystem to increase the output power of the high-voltage digital audio power amplifier system.

Preferably, in the above high-voltage digital audio power amplifier system, the first feedback module includes: a first resistor;

Wherein, one end of the first resistor is connected to the first input end of the first power amplifier loop, and the other end is connected to the output end of the first power amplifier loop;

The second feedback module includes: a second resistor;

Wherein, one end of the second resistor is connected to the first input end of the second power amplifier loop, and the other end is connected to the output end of the second power amplifier loop.

Preferably, in the above high-voltage digital audio power amplifier system, the current source generating module includes: a first field effect tube, a second field effect tube, a third field effect tube, an operational amplifier, and a third resistor;

Wherein, the inverting input terminal of the operational amplifier is connected to the power supply voltage terminal, the non-inverting input terminal of the operational amplifier is connected to the first terminal of the third resistor, and the second terminal of the third resistor is The voltage input terminal is connected;

The drain of the first field effect tube is connected to the first end of the third resistor;

The drain of the second field effect tube is connected to the first input end of the first power amplifier loop;

The drain of the third field effect tube is connected to the second input end of the second power amplifier loop;

The grid of the first field effect tube, the grid of the second field effect tube, and the grid of the third field effect tube are all connected to the output terminal of the operational amplifier;

The source of the first field effect tube, the source of the second field effect tube, and the source of the third field effect tube are all connected to ground.

Preferably, in the above high-voltage digital audio power amplifier system, the resistance of the third resistor is twice the resistance of the first resistor.

Preferably, in the above high-voltage digital audio power amplifier system, the sixth end of the current source generating module is used to receive a control signal;

The control signal is used to control the current source generating module to be in different working states to match the resistance of the first subsystem and the second subsystem.

Preferably, in the above high-voltage digital audio power amplifier system, the current source generating module further includes: a fourth field effect tube, a fifth field effect tube, a sixth field effect tube, and a seventh field effect tube;

Wherein, the source electrodes of the fourth field effect tube and the fifth field effect tube are respectively connected to the drain electrodes of the second field effect tube;

Sources of the sixth field effect tube and the seventh field effect tube are respectively connected to drains of the third field effect tube;

The drain of the fourth field effect tube and the drain of the seventh field effect tube are respectively connected to the first input end of the first power amplifier loop;

The drain of the fifth field effect tube and the drain of the sixth field effect tube are respectively connected to the first input end of the second power amplifier loop;

The gates of the fourth FET, the fifth FET, the sixth FET, and the seventh FET all receive the control signal.

Preferably, in the above high-voltage digital audio power amplifier system, the control signal includes a first control signal and a second control signal;

The grids of the fourth field effect transistor and the sixth field effect transistor are both used to receive the first control signal;

The grids of the fifth field effect transistor and the seventh field effect transistor are both used to receive the second control signal;

When the first control signal is high, the second control signal is low; when the first control signal is low, the second control signal is high.

Preferably, in the above high-voltage digital audio power amplifier system, the high-voltage digital audio power amplifier system further includes: a common mode voltage generating module;

The second input terminal of the first power amplifier loop and the second input terminal of the second power amplifier loop are both connected to the output terminal of the common mode voltage generating module.

Preferably, in the above high-voltage digital audio power amplifier system, the common-mode voltage generating module includes: a fourth resistor, a fifth resistor, a sixth resistor, and a capacitor;

The first end of the fourth resistor is connected to the power supply voltage end, the second end of the fourth resistor is connected to the first end of the fifth resistor, and the second end of the fifth resistor is connected to ground ;

The first end of the sixth resistor is connected to the second end of the fourth resistor, the second end of the sixth resistor is connected to the first end of the capacitor, and the second end of the capacitor is connected to ground;

The connection node of the sixth resistor and the capacitor serves as an output terminal of the common mode voltage generation module.

Preferably, in the above high-voltage digital audio power amplifier system, the resistance of the fourth resistor and the resistance of the fifth resistor are the same.

Preferably, in the above-mentioned high-voltage digital audio power amplifier system, the output voltage of the common-mode voltage generating module is half of the voltage supply end of the power supply.

Preferably, in the above high-voltage digital audio power amplifier system, the periods of the control signal, the PWMP signal and the PWMN signal are the same.

Compared with the prior art, the technical solution provided by the present invention has the following advantages:

A high-voltage digital audio power amplifier system provided by the present invention is provided with a current source generating module for supplying current to the first subsystem and the second subsystem, so that the high-voltage digital audio power amplifier system operates at a higher level Voltage range, which in turn increases the output power of the high-voltage digital audio power amplifier system.

BRIEF DESCRIPTION

In order to more clearly explain the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only This is an embodiment of the present invention. For those of ordinary skill in the art, without paying any creative labor, other drawings may be obtained according to the provided drawings.

1 is a schematic structural diagram of a high-voltage digital audio power amplifier system according to an embodiment of the present invention;

2 is another schematic structural diagram of a high-voltage digital audio power amplifier system according to an embodiment of the present invention;

3 is a schematic structural diagram of a current source generating module according to an embodiment of the present invention;

4 is a schematic structural diagram of a common-mode voltage generation module provided by an embodiment of the present invention;

5 is a schematic diagram of a waveform of charging and discharging of a first capacitor provided by an embodiment of the present invention;

6 is another schematic structural diagram of a high-voltage digital audio power amplifier system according to an embodiment of the present invention;

7 is another schematic structural diagram of a current source generating module according to an embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be described clearly and completely in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present invention.

In order to make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be described in further detail in conjunction with the accompanying drawings and specific embodiments.

Referring to FIG. 1, FIG. 1 is a schematic structural diagram of a high-voltage digital audio power amplifier system according to an embodiment of the present invention. Its function is to convert a PWM signal processed by a digital module into an analog signal. The high-voltage digital audio power amplifier system includes: A subsystem, a second subsystem, a first feedback module 13, a second feedback module 17, and a current source generating module 14;

The first subsystem includes: a first current source module 11 and a first power amplifier loop 12, the output end of the first current source module 11 is connected to the first input end Vip of the first power amplifier loop 12, The input terminal of the first current source module 11 is used as the signal input terminal of the first subsystem to receive the PWMP signal, and the output terminal of the first power amplifier loop 12 is used as the output terminal of the first subsystem VOP;

The second subsystem includes: a second current source module 15 and a second power amplifier loop 16, the output terminal of the second current source module 15 is connected to the first input terminal Vin of the second power amplifier loop 16, The input terminal of the second current source module 15 is used as the signal input terminal of the second subsystem to receive the PWMN signal, and the output terminal of the second power amplifier loop 16 is used as the output terminal of the second subsystem VON;

One end of the first feedback module 13 is connected to the first input end Vip of the first power amplifier loop 12, and the other end is connected to the output end of the first power amplifier loop 12;

One end of the second feedback module 17 is connected to the first input terminal Vin of the second power amplifier loop 16, and the other end is connected to the output end of the second power amplifier loop 16;

It can be known from the foregoing description that a high-voltage digital audio power amplifier system provided by the present invention is provided with a current source generating module for providing current to the first subsystem and the second subsystem, so that the high-voltage digital audio power amplifier The system works in a higher voltage range, thereby increasing the output power of the high-voltage digital audio power amplifier system.

Further, as shown in FIG. 1, the high-voltage digital audio power amplifier system further includes: a common-mode voltage generating module 18;

The second input terminal of the first power amplifier loop 12 and the second input terminal of the second power amplifier loop 16 are both connected to the output terminal VREF of the common mode voltage generating module 18.

In this embodiment, the common-mode voltage generation module 18 is used to generate a common-mode voltage signal for maintaining the stability of the output signals of the first current source module 11 and the second current source module 12.

Wherein, the output terminal voltage of the common mode voltage generating module 18 is half of the power supply voltage supply terminal VDD.

Further, referring to FIG. 2, FIG. 2 is another schematic structural diagram of a high-voltage digital audio power amplifier system according to an embodiment of the present invention. The first current source module 11 includes a first current source IDAC1, a second current source IDAC2, and a switch A. And switch B.

The input terminal of the first current source IDAC1 is connected to the power supply voltage terminal VDD, the output terminal of the first current source IDAC1 is connected to the input terminal of the switch A, the output terminal of the switch A is connected to the input terminal of the switch B, and the output terminal of the switch B The second current source IDAC2 is connected to the ground, and the control terminals of the switch A and the switch B serve as input terminals of the first current source module 11 for receiving the PWMP signal.

Further, as shown in FIG. 2, the first power amplifier loop 12 includes a first operational amplifier 21, a power amplifier loop drive module 23, a first capacitor C1, a field effect transistor P1, and a field effect transistor N1;

The inverting input terminal of the first operational amplifier 21 is connected to the output terminal of the first current source module 11, the non-inverting input terminal of the first operational amplifier 21 is connected to the output terminal VREF of the common-mode voltage generating module 18, and the first operational amplifier 21 Is connected to the input end of the power amplifier loop drive module 23, the first output end of the power amplifier loop drive module 23 is connected to the gate of the field effect transistor P1, and the power amplifier loop drive module 23 Is connected to the gate of the field effect transistor N1.

The source of the field effect transistor P1 is connected to the voltage input terminal PVDD, the drain of the field effect transistor P1 is connected to the drain of the field effect transistor N1, and the source of the field effect transistor N1 is grounded. The connection node of the field effect transistor P1 and the field effect transistor N1 serves as the output terminal VOP of the first power amplifier loop.

The first terminal of the first capacitor C1 is connected to the output terminal of the first operational amplifier 21, and the second terminal is connected to the inverting input terminal of the first operational amplifier 21.

Further, as shown in FIG. 2, the second current source module 15 includes a third current source IDAC3, a fourth current source IDAC4, a switch C, and a switch D.

The input terminal of the third current source IDAC3 is connected to the power supply voltage terminal VDD, the output terminal of the third current source IDAC3 is connected to the input terminal of the switch C, the output terminal of the switch C is connected to the input terminal of the switch D, and the output terminal of the switch D The fourth current source IDAC4 is connected to the ground, and the control terminals of the switch C and the switch D serve as input terminals of the second current source module 15 for receiving the PWMN signal.

Further, as shown in FIG. 2, the second power amplifier loop 16 includes a second operational amplifier 22, a power amplifier loop drive module 24, a second capacitor C2, a field effect transistor P2, and a field effect transistor N2;

The inverting input terminal of the second operational amplifier 22 is connected to the output terminal of the second current source module 16, the non-inverting input terminal of the second operational amplifier 22 is connected to the output terminal VREF of the common mode voltage generating module 18, and the second operational amplifier 22 Is connected to the input end of the power amplifier loop drive module 24, the first output end of the power amplifier loop drive module 24 is connected to the gate of the field effect transistor P2, and the power amplifier loop drive module 24 Is connected to the gate of the field effect transistor N2.

The source of the field effect transistor P2 is connected to the voltage input terminal PVDD, the drain of the field effect transistor P2 is connected to the drain of the field effect transistor N2, and the source of the field effect transistor N2 is grounded. The connection node of the field effect transistor P2 and the field effect transistor N2 serves as the output terminal VON of the second power amplifier loop.

The first terminal of the second capacitor C2 is connected to the output terminal of the second operational amplifier 22, and the second terminal is connected to the inverting input terminal of the second operational amplifier 22.

Further, as shown in FIG. 2, the first feedback module 13 includes: a first resistor Rfb1;

Wherein, one end of the first resistor Rfb1 is connected to the first input end of the first power amplifier loop 12 and the other end is connected to the output end of the first power amplifier loop 12;

The second feedback module 16 includes: a second resistor Rfb2;

Wherein, one end of the second resistor Rfb2 is connected to the first input end of the second power amplifier loop 16, and the other end is connected to the output end of the second power amplifier loop 16.

Further, referring to FIG. 3, FIG. 3 is a schematic structural diagram of a current source generating module according to an embodiment of the present invention. The current source generating module 14 includes: a first field effect transistor M1, a second field effect transistor M2, and a Three field effect transistors M3, operational amplifier 31 and third resistor R3;

Wherein, the inverting input terminal of the operational amplifier 31 is connected to the power supply voltage terminal VDD, the non-inverting input terminal of the operational amplifier 31 is connected to the first terminal of the third resistor R3, and the third resistor R3 The second terminal of the is connected to the voltage input terminal PVDD;

The drain of the first field effect transistor M1 is connected to the first end of the third resistor R3;

The drain of the second field effect transistor M2 is connected to the first input terminal Vip of the first power amplifier loop 12;

The drain of the third field effect transistor M3 is connected to the second input terminal Vin of the second power amplifier loop 16;

The gate of the first field effect tube M1, the gate of the second field effect tube M2, and the gate of the third field effect tube M3 are all connected to the output terminal of the operational amplifier 31;

The source of the first field effect tube M1, the source of the second field effect tube M2, and the source of the third field effect tube M3 are all grounded.

Further, the resistance of the third resistor R3 is twice the resistance of the first resistor Rfb1.

The first field effect tube M1, the second field effect tube M2, and the third field effect tube M3 are all N-type field effect tubes.

The first MOSFET M1, the second MOSFET M2, and the third MOSFET M3 have the same width to length ratio.

Further, referring to FIG. 4, FIG. 4 is a schematic structural diagram of a common-mode voltage generation module provided by an embodiment of the present invention. The common-mode voltage generation module 18 includes: a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6 and capacitor C;

The first end of the fourth resistor R4 is connected to the power supply voltage terminal PVDD, the second end of the fourth resistor R4 is connected to the first end of the fifth resistor R5, and the fifth resistor R5 Ground connection at the second end;

The first end of the sixth resistor R6 is connected to the second end of the fourth resistor R4, the second end of the sixth resistor R6 is connected to the first end of the capacitor C, and the first end of the capacitor C Two-terminal ground connection;

The connection node of the sixth resistor R6 and the capacitor C serves as the output terminal VREF of the common-mode voltage generating module 18.

Further, the resistance of the fourth resistor R4 is the same as the resistance of the fifth resistor R5.

Based on the high-voltage digital audio power amplifier system provided above, the high-voltage digital audio power amplifier system can only work normally when the output terminal voltage VREF of the common-mode voltage generation module 18 is half of the power supply voltage terminal VDD.

Since the working principles of the first subsystem and the second subsystem are the same, the following describes and explains the working principles of the first subsystem.

When VOP="1", the output VOP of the first subsystem charges the first capacitor C1 through the first resistor Rfb1 and the current source generating module 14, and the charging current is marked as I _{Rfb1_a} ;

When VOP="0", the output VOP of the first subsystem discharges the first capacitor C1 through the first resistor Rfb1 and the current source generating module 14, and the discharged current is marked as I _{Rfb1_b} ;

Because in the case where the high-voltage digital audio power amplifier system works normally, I _{Rfb1_a} = I _{Rfb1_b} and it is marked as I _Rfb1 .

That is, I _{Rfb1_a} = I _{Rfb1_b} = I _Rfb1

Where, I _Rfb1 represents the current value at which the output terminal VOP of the first subsystem charges or discharges the first capacitor C1 through the first resistor Rfb1 and the current source generating module 14.

Since the output terminal voltage VREF of the common-mode voltage generating module 18 is half of the voltage supply terminal VDD, it will be obtained as follows:

It can be seen with reference to FIGS. 2 and 3 that

Further available,

Wherein, I _SNK1 represents the current value provided by the current source generating module 14 for the first subsystem.

Further available,

As shown in FIG. 3, since the resistance of the third resistor R3 is twice the resistance of the first resistor Rfb1, and the first field effect transistor M1, the second field effect transistor M2 and all The aspect ratio of the third field effect tube M3 is the same.

So it can be concluded that

Wherein, I _SNK2 represents the current value provided by the current source generating module 14 for the second subsystem.

Furthermore, by analyzing the relationship between the input duty cycle and the output signal, it can be found that, referring to FIG. 5, FIG. 5 is a schematic diagram of a waveform of charging and discharging of a first capacitor provided by an embodiment of the present invention. The first capacitor C1 is in a PWMP The charge and discharge in the cycle is divided into 4 stages.

At the T1 stage: PWMP="1", high level, VOP="1", high level, the first current source IDAC1 charges the first capacitor C1, and the output terminal VOP of the first subsystem passes through the first resistor Rfb1 and the current source generating module 14 charge the first capacitor C1. At this time, the current of the first capacitor C1 is:

I _{C1_T1} = I _DAC +I _Rfb1

In the T2 phase: PWMP="1", high level, VOP="0", low level, the first current source IDAC1 charges the first capacitor C1, the output terminal VOP of the first subsystem passes through the first resistor Rfb1 and the current source generating module 14 discharge the first capacitor C1. At this time, the current of the first capacitor C1 is:

I _{C1_T2} =I _DAC -I _Rfb1

In the T3 stage: PWMP="0", low level, VOP="0", low level, the second current source IDAC2 discharges the first capacitor C1, and the output terminal VOP of the first subsystem passes through the first resistor Rfb1 and the current source generating module 14 discharge the first capacitor C1. At this time, the current of the first capacitor C1 is:

I _{C1_T3} = -I _DAC -I _Rfb1

At the T4 stage: PWMP="0", low level, VOP="1", high level, the second current source IDAC2 discharges the first capacitor C1, the output terminal VOP of the first subsystem passes through the first resistor Rfb1 and the current source generating module 14 charge the first capacitor C1. At this time, the current of the first capacitor C1 is:

I _{C1_T4} = -I _DAC +I _Rfb1

Since the first subsystem is in normal operation, the charge and discharge of the first capacitor C1 are balanced, that is,

I _{C1_T1} ×t1+I _{C1_T2} ×t2=-I _{C1_T3} ×t3-I _{C1_T4} ×t4

Wherein, t1, t2, t3, and t4 are the time in each stage, and I _DAC is the current of the first current source IDAC1 and the second current source IDAC2.

By sorting out the above formula,

I _DAC ×(t1+t2)-I _DAC ×(t3+t4)=I _Rfb1 ×(t2+t3)-I _Rfb1 ×(t1+t4)

Among them, t1+t2=D _IN ×T, t3+t4=(1-D _IN )×T, t1+t4=D _OUT ×T, t2+t3=(1-D _OUT )×T

Among them, D _IN is the duty cycle of PWMP, D _OUT is the duty cycle of VOP, T is the cycle of PWMP and VOP.

Tidy up,

From this,

Then the output voltage VOP of the first subsystem is:

VOP＝D _OUT ×PVDD

which is,

According to the above formula, VOP is a

For the common mode point, the 50% input signal with the duty cycle D _IN as the center.

Similarly, the output voltage VON of the second subsystem can be known, and will not be described here.

Then, the total output voltage V _OUT of the digital audio power amplifier system is,

V _OUT = VOP-VON

which is,

V _OUT = 2×Rfb1×I _DAC (2×D _IN -1)

It can be seen that the gain of the high-voltage digital audio power amplifier system is 2×Rfb1×I _DAC .

It can be known from the above description that a high-voltage digital audio power amplifier system provided by the present invention is provided with a current source generating module for providing current to the first subsystem and the second subsystem, so that the high-voltage digital audio power amplifier The system works in a higher voltage range, thereby increasing the output power of the high-voltage digital audio power amplifier system to enhance the loudness of the speaker.

Further, referring to FIG. 6, FIG. 6 is another schematic structural diagram of a high-voltage digital audio power amplifier system provided by an embodiment of the present invention. Unlike the embodiments shown in FIGS. 1 and 2, the sixth end of the current source generating module 14 Used to receive the control signal SW;

The control signal SW is used to control the current source generating module 14 to be in different working states, so as to match the resistances of the first subsystem and the second subsystem.

Wherein, the control signal SW, the PWMP signal and the PWMN signal have the same period.

In this embodiment, the current source generating module 14 is first used to provide current for the first subsystem and the second subsystem to increase the output power of the high-voltage digital audio power amplifier system, so that the high-voltage The digital audio power amplifier system works in a higher voltage range, thereby increasing the output power of the high-voltage digital audio power amplifier system, and secondly by setting a sixth terminal for receiving a control signal to control the current source adjustment module to be in a different working state To match the resistances of the first subsystem and the second subsystem, thereby improving the power supply rejection ratio of the digital audio power amplifier system to eliminate noise on the speakers.

Further, referring to FIG. 7, FIG. 7 is another schematic structural diagram of a current source generating module according to an embodiment of the present invention.

The current source generating module 14 further includes: a fourth field effect tube M4, a fifth field effect tube M5, a sixth field effect tube M6, and a seventh field effect tube M7;

The source electrodes of the fourth field effect transistor M4 and the fifth field effect transistor M5 are respectively connected to the drain electrodes of the second field effect transistor M2;

Sources of the sixth MOSFET M6 and the seventh MOSFET M7 are respectively connected to the drains of the third MOSFET M3;

The drain of the fourth field effect tube M4 and the drain of the seventh field effect tube M7 are respectively connected to the first input terminal Vip of the first power amplifier loop;

The drain of the fifth field effect transistor M5 and the drain of the sixth field effect transistor M6 are respectively connected to the first input terminal Vin of the second power amplifier loop;

The gates of the fourth field effect transistor M4, the fifth field effect transistor M5, the sixth field effect transistor M6, and the seventh field effect transistor M7 all receive the control signal.

In this embodiment, the control signal SW includes a first control signal SW1 and a second control signal SW2;

Setting the gate of the fourth field effect transistor M4 and the gate of the sixth field effect transistor M6 to receive the first control signal SW1; the gate of the fifth field effect transistor M5 and the The grid of the seventh field effect transistor M6 is used to receive the second control signal SW2;

When the first control signal SW1 is high, the second control signal SW2 is low; when the first control signal SW1 is low, the second control signal SW2 is high.

That is, when the fourth field effect transistor M4 and the sixth field effect transistor M6 are in the on state, the fifth field effect transistor M5 and the seventh field effect tube M7 are in the off state;

When the fifth field effect transistor M5 and the seventh field effect transistor M7 are in an on state, the fourth field effect transistor M4 and the sixth field effect tube M6 are in an off state.

Based on the above embodiment, the first MOSFET M1, the second MOSFET M2, and the third MOSFET M3 have the same width-to-length ratio. Therefore, the current _{I_M2} and the second The current I _{_M3 of the} three field effect transistors is the same.

If the fourth field effect transistor M4, the fifth field effect transistor M5, the sixth field effect transistor M6, and the seventh field effect transistor M7 are not provided, the second field effect transistor M2 starts from the first of the first power amplifier loop 12 The input terminal Vip draws or sinks current, and the third field effect transistor M3 draws or sinks current from the first input terminal Vin of the second power amplifier loop 16.

The following uses the current drawn by the second FET M2 as an example for description.

That is, when VOP="1", the output terminal VOP of the first subsystem charges the first capacitor C1 through the first resistor Rfb1 and the current source adjustment module 14, and the charged current is marked as I _{Rfb1_1} ;

As can be seen from Figures 6 and 7,

Where, I _SNK1 represents the current _{drawn by the} current source adjustment module 14 from the first input terminal Vip of the first power amplifier loop 12.

Further, since the output terminal voltage VREF of the common-mode voltage generating module 18 is half of the voltage supply terminal VDD, it will be obtained as follows:

Further available,

However, in the actual manufacturing process, the second field effect transistor M2 and the third field effect transistor M3 inevitably have deviations due to the manufacturing process, which leads to the current I _{_M2 of the} second field effect transistor M2 and the third field effect The current I _{_M3 of the} tube M3 is not exactly the same, then the current drawn from the first power amplifier loop 12 through the path of the second field effect tube M2 and the current drawn from the second power amplifier loop 16 through the path of the third field effect tube M3 It is not the same, which in turn makes the gains of the first and second subsystems inconsistent, resulting in poor suppression of power supply fluctuations and interference, that is, the power supply suppression of the high-voltage digital audio power amplifier system is lower than the PSRR performance.

Wherein, since the resistance of the third resistor R3 is twice the resistance of the first resistor Rfb1, that is,

R3＝2Rfb1

Further, it can be seen from the circuit diagram shown in FIG. 7,

among them,

Represents the error factor of the second FET,

Represents the error factor of the third FET.

In order to solve the above problem, the current source adjustment module 14 provided by the embodiment of the present invention switches to use the second field effect transistor M2 and the third field effect transistor M3 in different PWM cycles.

For example, when the first control signal SW1 is high and the second control signal SW2 is low, the second field effect transistor M2 is connected to the first field effect transistor M4 The first input terminal Vip of the power amplifier loop 12, the third field effect transistor M3 is connected to the first input terminal Vin of the second power amplifier loop 16 through the sixth field effect transistor M6;

When the first control signal SW1 is low and the second control signal SW2 is high, the second field effect transistor M2 is connected to the second power amplifier ring through the fifth field effect transistor M5 The first input terminal Vin of the circuit 16, the third field effect transistor M3 is connected to the first input terminal Vip of the first power amplifier loop 12 through the seventh field effect transistor M7.

In other words, the current drawn by the current source adjustment module 14 from the first input terminal Vip of the first power amplifier loop 12 and the first input terminal Vin of the second power amplifier loop 16

And I _SNK2

In turn, the current is the same, which solves the problem of PSRR performance degradation caused by irrational factors such as manufacturing process mismatch.

among them,

Since the output terminal VOP of the first subsystem charges the first capacitor C1 through the first resistor Rfb1 and the current source adjustment module, the current value is equal, and the calibration is I _Rfb1 , so we can know that

Tidy up,

Furthermore, by analyzing the relationship between the input duty cycle and the output signal, it can be found that the charging and discharging of the first capacitor C1 in one PWMP cycle is divided into four stages, as shown in FIG. 5.

At the T1 stage: PWMP="1", high level, VOP="1", high level, the first current source IDAC1 charges the first capacitor C1, and the output terminal VOP of the first subsystem passes through the first resistor Rfb1 and the current source adjustment module 14 charge the first capacitor C1. At this time, the current of the first capacitor C1 is:

I _{C1_T1} = I _DAC +I _Rfb1

At the T2 stage: PWMP="1", high level, VOP="0", low level, the first current source IDAC1 charges the first capacitor C1, and the output terminal VOP of the first subsystem passes through the first resistor Rfb1 and the current source adjustment module 14 discharge the first capacitor C1. At this time, the current of the first capacitor C1 is:

I _{C1_T2} =I _DAC -I _Rfb1

In the T3 stage: PWMP="0", low level, VOP="0", low level, the second current source IDAC2 discharges the first capacitor C1, and the output terminal VOP of the first subsystem passes through the first resistor Rfb1 and the current source adjustment module 14 discharge the first capacitor C1. At this time, the current of the first capacitor C1 is:

I _{C1_T3} = -I _DAC -I _Rfb1

At the T4 stage: PWMP="0", low level, VOP="1", high level, the second current source IDAC2 discharges the first capacitor C1, the output terminal VOP of the first subsystem passes through the first resistor Rfb1 and the current source adjustment module 14 charge the first capacitor C1. At this time, the current of the first capacitor C1 is:

I _{C1_T4} = -I _DAC +I _Rfb1

I _{C1_T1} ×t1+I _{C1_T2} ×t2=-I _{C1_T3} ×t3-I _{C1_T4} ×t4

By sorting out the above formula,

I _DAC ×(t1+t2)-I _DAC ×(t3+t4)=I _Rfb1 ×(t2+t3)-I _Rfb1 ×(t1+t4)

Among them, t1+t2=D _IN ×T, t3+t4=(1-D _IN )×T, t1+t4=D _OUT ×T, t2+t3=(1-D _OUT )×T.

Tidy up,

From this,

Then the output voltage VOP of the first subsystem is:

VOP＝D _OUT ×PVDD

which is,

According to the above formula, VOP is a

Similarly, the output voltage VON of the second subsystem can be known, which will not be repeated here.

V _OUT = VOP-VON

which is,

It can be seen that the gain of the high-voltage digital audio power amplifier system is

It can be known from the above description that a high-voltage digital audio power amplifier system provided by the present invention is first used to provide current for the first subsystem and the second subsystem by setting a current source adjustment module to improve the high-voltage digital audio The output power of the power amplifier system, so that the high-voltage digital audio power amplifier system works in a higher voltage range, thereby increasing the output power of the high-voltage digital audio power amplifier system.

Secondly, by receiving the control signal, it is used to control the current source adjustment module to be in different working states, so as to match the resistance of the first subsystem and the second subsystem, so that the first subsystem and the second subsystem The gains of the subsystems are equal, thereby improving the power supply rejection ratio of the digital audio power amplifier system to eliminate noise on the speakers.

The high-voltage digital audio power amplifier system provided by the present invention has been described in detail above. Specific examples are used to explain the principles and implementations of the present invention. The descriptions of the above embodiments are only used to help understand the method of the present invention. At the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation and scope of application. In summary, the content of this specification should not be understood as a limits.

It should be noted that the embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same and similar parts between the embodiments refer to each other. can. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant part can be referred to the description in the method part.

It should also be noted that in this article, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply these entities or operations There is any such actual relationship or order. Moreover, the terms "include", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that the elements inherent to a process, method, article, or device that include a series of elements, or are also included for these processes , Methods, articles or equipment inherent elements. Without more restrictions, the element defined by the sentence "include one..." does not exclude that there are other identical elements in the process, method, article or equipment that includes the element.

The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

A high-voltage digital audio power amplifier system is characterized by comprising: a first subsystem, a second subsystem, a first feedback module, a second feedback module and a current source generating module;

The first subsystem includes: a first current source module and a first power amplifier loop, the output end of the first current source module is connected to the first input end of the first power amplifier loop, the first current The input terminal of the source module is used as the signal input terminal of the first subsystem to receive the PWMP signal, and the output terminal of the first power amplifier loop is used as the output terminal of the first subsystem;

The second subsystem includes: a second current source module and a second power amplifier loop, the output end of the second current source module is connected to the first input end of the second power amplifier loop, the second current The input terminal of the source module is used as the signal input terminal of the second subsystem to receive the PWMN signal, and the output terminal of the second power amplifier loop is used as the output terminal of the second subsystem;

One end of the first feedback module is connected to the first input end of the first power amplifier loop, and the other end is connected to the output end of the first power amplifier loop;

One end of the second feedback module is connected to the first input end of the second power amplifier loop, and the other end is connected to the output end of the second power amplifier loop;

The first end of the current source generating module is connected to the first input end of the first power amplifier loop, the second end is connected to the first input end of the second power amplifier loop, and the third end is connected to the power supply Terminal, the fourth terminal is connected to the voltage input terminal, and the fifth terminal is connected to ground;

Wherein, the current source generating module is used to provide current for the first subsystem and the second subsystem to increase the output power of the high-voltage digital audio power amplifier system.
The high-voltage digital audio power amplifier system according to claim 1, wherein the first feedback module comprises: a first resistor;

Wherein, one end of the first resistor is connected to the first input end of the first power amplifier loop, and the other end is connected to the output end of the first power amplifier loop;

The second feedback module includes: a second resistor;

Wherein, one end of the second resistor is connected to the first input end of the second power amplifier loop, and the other end is connected to the output end of the second power amplifier loop.
The high-voltage digital audio power amplifier system according to claim 2, wherein the current source generating module includes: a first field effect tube, a second field effect tube, a third field effect tube, an operational amplifier, and a third resistor;

Wherein, the inverting input terminal of the operational amplifier is connected to the power supply voltage terminal, the non-inverting input terminal of the operational amplifier is connected to the first terminal of the third resistor, and the second terminal of the third resistor is The voltage input terminal is connected;

The drain of the first field effect tube is connected to the first end of the third resistor;

The drain of the second field effect tube is connected to the first input end of the first power amplifier loop;

The drain of the third field effect tube is connected to the second input end of the second power amplifier loop;

The grid of the first field effect tube, the grid of the second field effect tube, and the grid of the third field effect tube are all connected to the output terminal of the operational amplifier;

The source of the first field effect tube, the source of the second field effect tube, and the source of the third field effect tube are all connected to ground.
The high-voltage digital audio power amplifier system according to claim 3, wherein the resistance of the third resistor is twice the resistance of the first resistor.
The high-voltage digital audio power amplifier system according to claim 3, wherein the sixth end of the current source generating module is used to receive a control signal;

The control signal is used to control the current source generating module to be in different working states to match the resistance of the first subsystem and the second subsystem.
The high-voltage digital audio power amplifier system according to claim 5, wherein the current source generating module further comprises: a fourth field effect tube, a fifth field effect tube, a sixth field effect tube, and a seventh field effect tube;

Wherein, the source electrodes of the fourth field effect tube and the fifth field effect tube are respectively connected to the drain electrodes of the second field effect tube;

Sources of the sixth field effect tube and the seventh field effect tube are respectively connected to drains of the third field effect tube;

The drain of the fourth field effect tube and the drain of the seventh field effect tube are respectively connected to the first input end of the first power amplifier loop;

The drain of the fifth field effect tube and the drain of the sixth field effect tube are respectively connected to the first input end of the second power amplifier loop;

The gates of the fourth FET, the fifth FET, the sixth FET, and the seventh FET all receive the control signal.
The high-voltage digital audio power amplifier system according to claim 6, wherein the control signal includes a first control signal and a second control signal;

The grids of the fourth field effect transistor and the sixth field effect transistor are both used to receive the first control signal;

The grids of the fifth field effect transistor and the seventh field effect transistor are both used to receive the second control signal;

When the first control signal is high, the second control signal is low; when the first control signal is low, the second control signal is high.
The high-voltage digital audio power amplifier system according to claim 6, wherein the high-voltage digital audio power amplifier system further comprises: a common mode voltage generating module;

The second input terminal of the first power amplifier loop and the second input terminal of the second power amplifier loop are both connected to the output terminal of the common mode voltage generating module.
The high-voltage digital audio power amplifier system according to claim 8, wherein the common-mode voltage generating module includes: a fourth resistor, a fifth resistor, a sixth resistor, and a capacitor;

The first end of the fourth resistor is connected to the power supply voltage end, the second end of the fourth resistor is connected to the first end of the fifth resistor, and the second end of the fifth resistor is connected to ground ;

The first end of the sixth resistor is connected to the second end of the fourth resistor, the second end of the sixth resistor is connected to the first end of the capacitor, and the second end of the capacitor is connected to ground;

The connection node of the sixth resistor and the capacitor serves as an output terminal of the common mode voltage generation module.
The high-voltage data audio power amplifier system according to claim 9, wherein the resistance of the fourth resistor is the same as the resistance of the fifth resistor.
The high-voltage data audio power amplifier system according to claim 7, wherein the output terminal voltage of the common-mode voltage generating module is half of the power supply voltage supply terminal.
The high-voltage digital audio power amplifier system according to claim 1, wherein the sixth end of the current source generating module is used to receive a control signal;

The control signal is used to control the current source generating module to be in different working states, so as to match the resistance of the first subsystem and the second subsystem.
The high-voltage digital audio power amplifier system according to claim 12, wherein the control signal, the PWMP signal and the PWMN signal have the same period.