WO2012028017A1 - Audio power amplifier and method for switching audio power amplification modes - Google Patents

Abstract

An audio power amplifier and a method for switching audio power amplification modes, performing switching of power amplification modes to meet requirements of electronic products for power consumption and electromagnetic interference (EMI) in different function modes. The method involves: when a device in which a power amplifier exists determines that the power consumption corresponding to the function mode that the device is currently in is lower than a power consumption threshold, a switch array unit (2) is indicated switching on a Class AB drive unit (3); when it is determined that the power consumption is greater than or equal to the power consumption threshold, and a function unit being more sensitive to EMI has been turned on, a control signal for indicating switching on the Class AB drive unit (3) is sent to the switch array unit (2); when it is determined that the power consumption is greater than or equal to the power consumption threshold, and none of function units being more sensitive to EMI has been turned on, the switch array unit (2) is indicated switching on a Class D modulation unit (4).

Description

 Audio power amplifier and audio power amplifier mode switching method The present application claims to be submitted to the Chinese Patent Office on June 22, 2010, application number 201010209833.0, and the invention titled "an audio power amplifier and audio power amplifier mode switching method" Chinese patent Priority of the application, the entire contents of which are incorporated herein by reference. Technical field

 The present invention relates to the field of electronic circuit design, and in particular, to an integrated circuit audio power amplifier and a method for switching an audio power amplifier mode using the audio power. Background technique

 The audio power amplifier is an indispensable device for audio back-end processing. Its main function is to amplify the audio signal and output it to the terminal receiver, such as headphones, speakers and so on. Currently, audio power amplifiers are divided into two categories according to their operating modes: one is a Class AB power amplifier, and the other is a Class D power amplifier.

 Class D power amplifier, as shown in Figure 1, the output is a discrete signal, the power tube of the Class D power amplifier operates in a switching state, and the Class D power amplifier is used for audio amplifiers with high output efficiency, but due to its The output signal has a large amplitude change in transient state. For example, the switching frequency is above 200 kHz. Therefore, the audio power amplifier with Class D power amplifier has large high-frequency energy, that is, EMI (electromagnetic interference) is large. Suitable for portable audio electronic systems that are sensitive to cockroaches.

 Class ΑΒ power amplifier, as shown in Figure 1, the output is a continuous signal, the power tube of the Class AB power amplifier works in a continuous state, the continuous signal in the output audio band, no high frequency energy, so EMI is small; Since the power tube operates in a continuous state, a large part of the energy is dissipated on the power tube. Therefore, the output efficiency of the audio power amplifier using the Class AB power amplifier is low.

In summary, the two types of power amplifiers have different operating states, and currently the two types of power amplifiers are adopted. Independent design, designed as separate integrated circuits. In portable audio electronic systems, the audio back-end equipment either selects the Class AB power amplifier for the audio amplifier or the Class D power amplifier for the audio amplifier. The drawback of this approach is that there may be multiple functions for an audio electronic product, and different functions have different power consumption and EMI requirements. For example, in a portable multimedia audio system, after decoding an audio data file on a storage medium (such as Flash), the music playback requires low power consumption and long time, and the EMI requirement is not strict; and the multimedia audio system performs FM ( Frequency Modulation, in order to obtain a clearer audio signal, a lower chirp is required to avoid high frequency interference affecting the sensitivity of FM reception; therefore, if a Class D power amplifier is set in the portable multimedia audio system for audio The power amplifier can meet the power consumption and EMI requirements in the music playback mode. However, due to the large EMI of the Class D power amplifier, it cannot meet the power consumption and EMI requirements in the FM mode. Similarly, if it is in the portable The Class AB power amplifier is set in the multimedia audio system. Although it can meet the power consumption and EMI requirements in the FM mode, the output efficiency of the Class AB power amplifier is low, so it cannot meet the power consumption and EMI in the music playback mode. Claim.

 At present, the actual audio products have a wide variety of complex functions (such as portable multimedia speakers, portable MP3, etc.), and the requirements for EMI and power consumption are different under different functions. For such electronic products, Only the Class AB power amplifier or the Class D power amplifier can be selected for audio power amplifier processing, which may meet the EMI and power consumption requirements of some functions, but the EMI and power consumption requirements for other functions are not satisfied. Summary of the invention

 The invention provides a method for switching an audio power amplifier and an audio power amplifier mode, so as to realize a power amplifier mode switching, which satisfies requirements for power consumption and EMI of electronic products in different functional modes.

 An audio power amplifier comprising a Class AB driving unit, a Class D modulation unit, and a power output unit, further comprising:

a preamplifier unit, configured to differentially amplify the received single-ended audio voltage signal to obtain two dual-ended differential signals and output the same; An external logic control port, connected to the switch array unit, for outputting a control signal to instruct the switch array unit to turn on the Class AB drive unit or the Class D modulation unit;

 a switch array unit, further connected to the preamplifier unit, configured to turn on a Class AB driving unit or a Class D modulation unit according to a control signal output by the external logic control port; and output the preamplifier unit Converting the differential signal into a first differential signal or a second differential signal corresponding to the turned-on Class AB driving unit or the Class D modulation unit;

 The Class AB driving unit is connected to the switch array unit, and configured to perform audio power amplifier processing on the first differential signal output by the switch array unit when the switch array unit turns on the Class AB driving unit, and Outputting a first differential signal after the audio power amplifier is processed;

 The Class D modulation unit is connected to the switch array unit, and configured to perform audio power amplifier processing on the second differential signal output by the switch array unit when the switch array unit turns on the Class D modulation unit. And outputting a second differential signal after the audio power amplifier processing;

 And an output selection unit, which is respectively connected to the Class AB driving unit and the Class D modulation unit, for performing amplification processing on the first differential signal of the Class AB driving unit and outputting; and outputting a second output to the Class D modulation unit The differential signal is processed and output;

 The power output unit is connected to the output selection unit for processing a signal output by the output selection unit and outputting the signal to a load.

 A method for implementing audio power amplifier mode switching includes:

 The preamplifier unit of the audio power amplifier differentially amplifies the received single-ended audio voltage signal to obtain two double-ended differential signals and outputs the signals;

 The external logic control port of the audio power amplifier outputs a control signal to indicate that the switch array unit of the audio power amplifier is turned on by the Class AB driving unit or the Class D modulation unit;

 The switch array unit turns on the audio power amplifier Class AB driving unit or the Class D modulation unit according to a control signal output by the external logic control port; and converts the differential signal output by the preamplifier unit into a connection a first differential signal or a second differential signal corresponding to the Class AB driving unit or the Class D modulation unit;

When the switch array unit turns on the Class AB drive unit, the Class AB drive list Performing an audio power amplifier processing on the first differential signal output by the switch array unit, and outputting a first differential signal after the audio power amplifier processing; and outputting, by the output selection unit of the audio power amplifier, the first differential signal output by the Class AB driving unit Performing amplification processing and outputting to a power output unit, and the power output unit processes the signal output by the output selection unit and outputs the signal to the load;

 When the switch array unit turns on the Class D modulation unit, the Class D modulation unit performs audio power amplifier processing on the second differential signal output by the switch array unit, and outputs a second differential signal after the audio power amplifier processing; An output selection unit of the audio power amplifier processes and outputs a second differential signal outputted by the Class D modulation unit, and the power output unit processes the signal output by the output selection unit and outputs the signal to the load.

 In the embodiment of the present invention, when the device where the audio power amplifier is located determines that the function mode currently in which the device is currently located is lower than the power consumption threshold, the control signal for indicating that the Class AB driving unit is turned on is sent to the switch array unit; When a functional unit with a greater sensitivity to EMI is turned on or equal to a power consumption threshold, a control signal for indicating that the Class AB driving unit is turned on is sent to the switch array unit; determining that the power consumption is higher than or equal to the power consumption threshold and not When the functional unit with high sensitivity to EMI is turned on, the control signal for turning on the Class D modulation unit is sent to the switch array unit, thereby switching the power amplifier mode according to the power consumption and EMI requirements of different functions of the electronic product. DRAWINGS

 1 is a schematic diagram of processing a audio signal by a power amplifier in the prior art;

 2 is a schematic structural diagram of an audio power amplifier according to an embodiment of the present invention;

 3 is a circuit structural diagram of a preamplifier circuit and a switch array unit of an audio power amplifier according to an embodiment of the present invention;

 4-1 is a schematic diagram of a circuit structure of an output selection unit and a power output unit in an audio power amplifier according to an embodiment of the present invention;

 4-2 is a second schematic structural diagram of a circuit of an output selection unit and a power output unit in an audio power amplifier according to an embodiment of the present invention;

4-3 is an output selection unit and a power output list in an audio power amplifier according to an embodiment of the present invention; The third schematic diagram of the circuit structure;

 Figure 4-4 is a schematic diagram showing the circuit structure of the Miller capacitor at the gate and drain terminals of the PP and the Miller capacitor at the gate and drain terminals of the PN based on the circuit shown in Figure 4-1;

 Figure 4-5 is a schematic diagram showing the circuit structure of the Miller capacitor at the gate and drain terminals of the PP and the Miller capacitor at the gate and drain terminals of the PN based on the circuit shown in Figure 4-2;

 4-6 is a schematic diagram of a circuit structure in which a Miller capacitance is set at a gate terminal and a drain terminal of a PP and a Miller capacitor is disposed at a gate terminal and a drain terminal of the PN based on the circuit shown in FIG. 4-3;

 FIG. 5 is a flow chart of switching an audio power amplifier mode using an audio power amplifier according to an embodiment of the present invention. detailed description

 In order to meet the power consumption and EMI requirements of the electronic product in different functional modes, an embodiment of the present invention provides an audio power amplifier including a Class AB driving unit, a Class D modulation unit, a power output unit, and a front end. Amplification unit, switch array unit, Class AB drive unit, Class D modulation unit, selection output unit and power output unit; external logic control port (ie S-MOD) according to the current functional mode of the electronic product for power consumption, EMI The indicator controls the switch array unit, and the output selection unit selects the Class AB drive unit or the Class D modulation unit for audio power amplifier processing. The audio power amplifier provided by the embodiment of the invention can select the audio power amplifier mode in the audio power amplifier to perform audio power amplifier processing according to the requirements of EMI and power consumption of the electronic product in different functional modes.

 The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

 2 is a schematic structural diagram of an audio power amplifier according to an embodiment of the present invention. The audio power amplifier includes, in addition to the Class AB driving unit, the Class D modulation unit, and the power output unit, the following:

 The preamplifier unit 1 is configured to differentially amplify the received single-ended audio voltage signal to obtain two dual-ended differential signals and output the signals.

An external logic control port, connected to the switch array unit 2, for outputting a control signal to The switch array unit 2 is turned on by the Class AB drive unit 3 or the Class D modulation unit 4.

 The switch array unit 2 is respectively connected to the preamplifier unit 1, the external logic control port, and is configured to turn on the Class AB drive unit 3 or the Class D modulation unit 4 according to the control signal output by the external logic control port; and preamplify The differential signal output by the unit 1 is converted into a first differential signal or a second differential signal corresponding to the turned-on Class AB driving unit 3 or the Class D modulation unit 4.

 The Class AB driving unit 3 is connected to the switch array unit 2, and is configured to perform, when the switch array unit 2 turns on the Class AB driving unit 3, the first differential signal corresponding to the Class AB driving unit 3 outputted by the switch array unit 2 The audio power amplifier processes and outputs the first differential signal after the audio power amplifier processes.

 a Class D modulation unit 4, connected to the switch array unit 2, for outputting the second differential signal corresponding to the Class D modulation unit 4 outputted to the array unit 2 when the switch array unit 2 turns on the Class D modulation unit 4. The audio power amplifier processing is performed, and the second differential signal after the audio power amplifier processing is output.

 The output selection unit 5 is respectively connected to the Class AB driving unit 3 and the Class D modulation unit 4 for amplifying and outputting the first differential signal outputted by the Class AB driving unit 3; and is also used for outputting the Class D modulation unit 4. The second differential signal is processed and output.

 The power output unit 6 is connected to the output selection unit 5 for processing the signal output from the output selection unit 5 and outputting it to the load.

 The Class AB driving unit 3 is specifically applied to: perform audio power amplifier processing on the first differential signal outputted by the switch array unit 2 to obtain a first audio signal and a second audio signal and output the same.

 The Class D modulation unit 4 is specifically applied to: perform audio power amplifier processing on the second differential signal outputted by the switch array unit 2 to obtain a third audio signal and a fourth audio signal and output the same.

The output selection unit 5 is specifically configured to: copy the first audio signal outputted by the Class AB driving unit 3 to obtain two first audio signals, and perform amplification processing on one of the first audio signals to obtain a fifth audio signal, and Outputting a fifth audio signal and another first audio signal; for copying the second audio signal outputted by the Class AB driving unit 3, obtaining two second audio signals, and amplifying one of the second audio signals Sixth audio signal, and output a sixth audio signal and another second audio signal; and a third audio signal and a fourth audio signal for outputting the Class D modulation unit 4, respectively, and outputting two third audio signals and two fourth audio signals signal.

 The power output unit 6 is specifically configured to: invert and superimpose the first audio signal and the fifth audio signal to obtain a seventh audio signal and output the signal to the load; and use the second audio signal and the sixth audio signal to reverse Phase, superposition processing, obtaining an eighth audio signal and outputting to the load; for inverting and superimposing the two third audio signals, obtaining a ninth audio signal and outputting to the load; for using the two fourth audio signals The inversion and superposition processing are performed to obtain a tenth audio signal and output to the load.

 In the embodiment of the present invention, the single-ended audio voltage signal is represented by an IN signal; the two differential signals are an INP (Input-Positive) signal and an INN (Input-Negative); The differential signals corresponding to unit 3 are INP1 signal and INN1 signal; the differential signals corresponding to Class D modulation unit 4 are I P2 signal and INN2 signal; the first audio signal is VOP1 signal; the second audio signal is VON1 signal; third audio The signal is a VOP2 signal; the fourth audio signal is a VON2 signal; processing the first audio signal VOP1 to obtain a fifth audio signal as a VPG_P1 signal and another first audio signal (represented by VNG-P1); and a second audio signal VON1 Processing to obtain a sixth audio signal as a VPG_N1 signal and another second audio signal (indicated by VNG_N1); copying the third audio signal VOP2 to obtain two signals (the two signals are represented by VPG_P2 and VNG-P2, respectively), Copying the fourth audio signal VON2 to obtain two signals (the two signals are represented by VPG_N2 and VNG_N2, respectively) Seventh audio signal is a signal OUTP1; OUTN1 eighth signal is an audio signal; OUTP2 audio signal is a ninth signal; OUTN2 tenth signal is an audio signal. The principle of audio power amplifier processing using the above audio power amplifier, ^:

 Step 1. The preamplifier unit 1 receives the audio signal IN signal input by the single end, and differentially amplifies the IN signal to obtain a differential signal INP signal and an INN signal, and sends the two differential signals to the switch array unit. 2.

Step 2, the switch array unit 2 turns on the Class AB drive unit 3 or the Class D modulation unit 4 according to the control signal input by the S MOD; when the Class AB drive unit 3 is turned on, it will receive The two differential signals are converted into an INP1 signal and an INN1 signal, and output to the Class AB driving unit 3. When the Class D modulation unit 4 is turned on, the received two differentials are converted into an INP2 signal and an INN2 signal, and output to the Class. D modulation unit 4.

 In this step, the device where the audio power amplifier is located sends a control signal to the switch array unit 2 through the S-MOD according to the current power consumption and EMI requirement indicators; the control signal can be represented by high and low level signals. For example, when the current functional mode of the electronic product is sensitive to EMI, when the high-level control signal is sent to the switch array unit 2 through the S-MOD, the switch array unit 2 is instructed to turn on the Class AB drive unit 3; The functional mode in which the product is currently required requires lower power consumption, is insensitive to EMI, and sends a low level control signal to the switch array unit 2 through the S_MOD, indicating that the switch array unit 2 turns on the Class D modulation unit 4.

 Step 3: When the Class AB driving unit 3 is turned on, the Class AB driving unit 3 performs power amplifier processing on the received INP1 signal and the INN1 signal to obtain a VOP1 signal and a VON1 signal, and outputs the signal to the output selecting unit 5; or

 When the Class D modulation unit 4 is turned on, the Class D modulation unit 4 performs power amplifier processing on the received INP2 signal and the INN2 signal to obtain a VOP2 signal and a VON2 signal, and outputs it to the output selection unit 5.

 The VOP1 signal and the VON1 signal are continuous voltage signals; the VOP2 signal and the VON2 signal are discrete voltage signals, and the VOP2 signal and the VON2 signal can be classified into a PWM (Pulse-Width Modulation) signal according to a modulation method, and SDM (Sigma-Delta Modulation) ) Signal.

 Step 4: When the switch array unit 2 turns on the Class AB driving unit 3, the output selection unit 5 processes the received VOP1 signal and the VON1 signal to obtain a VPG_P1 signal, a VNG_P1 signal, a VPG_N1 signal, and a VNG-N1 signal. And output to the power output unit 6;

 When the switch array unit 2 turns on the Class D modulation unit 4, the received VOP2 signal and the VON2 signal are processed to obtain a VPG_P2 signal, a VNG_P2 signal, a VPG_N2 signal, and a VNG-N2 signal, and output to the power output unit 6 .

Step 5. The power output unit 6 pairs the received VPG-P1 signal, the VNG-P1 signal, and the VPG N1. The signal and the VNG_N1 signal are processed to obtain the OUTP1 signal and OUTN1 and output to the load; the power output unit 6 processes the received VPG-P2 signal, the VNG_P2 signal, the VPG-N2 signal, and the VNG-N2 signal to obtain the OUTP2 signal and the OUTN2. And output to the load.

 In the above step 4, the output selection unit 5 obtains the VPG_P1 signal, the VNG-P1 signal, the VPG_N1 signal, and the VNG_N1 signal, specifically: dividing the received VOP1 signal into two paths, and amplifying one of the VOP1 signals to obtain VPG_P1. The signal is not processed by the other VOP1 signal, that is, the VNG_P1 signal is the same as the VOP1 signal; the received VON1 signal is divided into two paths, and one of the VON1 signals is amplified to obtain a VPG_N1 signal, and the other VON1 signal is not processed, that is, VNG – The N1 signal is the same as the VON1 signal.

 The output selection unit 5 obtains the VPG_P2 signal, the VNG_P2 signal, the VPG_N2 signal, and the VNG_N2 signal, specifically: the output selection unit 5 divides the received VOP2 signal into two paths, and does not process the two VOP2 signals, respectively, and obtains the VPG_P2 signal, The VNG_P2 signal; the output selection unit 5 divides the received VON2 signal into two paths, and does not process the two VON2 signals to obtain the VPG-N2 signal and the VNG-N2 signal, respectively.

 In step 5, the power output unit 6 obtains the OUTP1 signal and the OUTN1, specifically: the power output unit 6 inverts the received VPG_P1 signal and the VNG_P1 signal, respectively, to obtain an inverted VPG-P1 signal and an inverted VNG- P1 signal, and superimposing the inverted VPG-P1 signal and the inverted VNG_P1 signal to obtain an OUTP1 signal; the power output unit 6 inverts the received VPG-N1 signal and the VNG-N1 signal respectively to obtain an inverted phase The VPG-N1 signal, the inverted VNG-N1 signal, and the inverted VPG-N1 signal and the inverted VNG_N1 signal are superimposed to obtain an OUTN1 signal.

The power output unit 6 inverts the received VPG-P2 signal and the VNG_P2 signal, respectively, to obtain an inverted VPG-P2 signal, an inverted VNG-P2 signal, and the inverted VPG-P2 signal and the inverted VNG P2. The signals are superimposed to obtain an OUTP2 signal; the power output unit 6 inverts the received VPG-N2 signal and the VNG-N2 signal, respectively, to obtain an inverted VPG_N2 signal, an inverted VNG-N2 signal, and the inverted VPG. – The N2 signal and the inverted VNG N2 signal are superimposed to obtain the OUTN2 signal. The specific implementation of the above audio power amplifier of the present invention will be described in detail below in conjunction with actual application.

 As shown in FIG. 3, it is a circuit structure diagram of a preamplifier unit 1 and a switch array unit 2 in an audio power amplifier according to an embodiment of the present invention. The preamplifier unit 1 includes an operational amplifier 11, a first resistor R11, and The second resistor R12, the third resistor 21, the fourth resistor R22, the fifth resistor 31 and the sixth resistor R32, wherein the resistances of the first resistor R11 and the second resistor R12 may be the same, the third resistor R21 and the fourth resistor R22 The resistance values of the fifth resistor R31 and the sixth resistor R32 may be the same; the switch array unit 2 includes a first switch S01, a second switch S02, a third switch S03, a fourth switch S04, and a fifth switch S11. a sixth switch S12, a seventh switch S13, and an eighth switch S14, wherein:

 The IN signal is input to the positive pole of the operational amplifier 11 through the external coupling capacitor Cin and the first resistor R11, and the operational amplifier 11 uses a fully differential architecture to differentially amplify the single-ended input signal IN signal to obtain a differential double-ended audio signal. The open loop gain of the arithmetic unit 11 is generally 80 dB, and the noise in the audio band is low, generally lower than 1 OuVrms.

 The DC bias voltage Bias is input to the negative terminal of the operational amplifier 11 through a second resistor R12. The DC bias voltage Bias is a DC bias voltage supplied internally by the system and is generally half the value of the system power supply.

 The third resistor R21 in the preamplifier unit 1 and the first switch S01 in the switch array unit 2 are connected in series to form a first feedback circuit connected to the input terminal of the operational amplifier 11 and the output terminal of the operational amplifier 11. Between the feedback gain of the first feedback circuit = R2\ /R\

The third resistor R21 and the fifth resistor R31 in the preamplifier unit 1 and the fifth switch S11 in the switch array unit 2 are connected in series to form a second feedback circuit, which is connected to the input terminal and the power of the operational amplifier 11. Between the outputs of the output unit 6; the feedback gain of the second feedback circuit = (i?21 + i?31) / l; when the switch array unit 2 turns on the Class D modulation unit 4, the S-MOD controls the second The switch S02 is turned on and the sixth switch S12 is turned off; when the switch array unit 2 turns on the Class AB driving unit 3, the S-MOD controls the second switch S02 to be turned off, and the sixth switch S12 is turned on. The positive output terminals of the operational amplifier 11 are respectively connected with a third switch S03 and a seventh switch S13, which constitute a first output end and a second output end, and the first output end is used for outputting an INP2 signal for the Class D modulation unit 4, and a second output. The terminal is used to output the INP1 signal for the Class AB driving unit 3; the negative output terminal of the operational amplifier 11 is respectively connected with the fourth switch S04 and the eighth switch S14, which constitute a third output end and a fourth output end, and the third output end is used for The I N2 signal is outputted for the Class D modulation unit 4, and the fourth output is used to output the INN1 signal for the Class AB drive unit 3; when the switch array unit 2 needs to be turned on the Class AB drive unit 3, the fifth switch S11, the sixth is controlled. The switch S12, the seventh switch S13 and the eighth switch S14 are turned on, and the first switch S01, the second switch S02, the third switch S03 and the fourth switch S04 are controlled to be turned off; when the switch array unit 2 needs to be turned on, the Class D modulation unit is turned on. At 4 o'clock, the first switch S01, the second switch S02, the third switch S03, and the fourth switch S04 are turned on, and the fifth switch S11, the sixth switch S12, the seventh switch S13, and the eighth switch S14 are controlled to be turned off.

 Referring to FIG. 4-1, it is a schematic diagram of a circuit structure of an output selection unit 5 and a power output unit 6 in an audio power amplifier according to an embodiment of the present invention:

 The power output unit 6 is composed of an H-bridge power tube, and the H-bridge power tube includes: two NMOS transistors (represented by PN1 and PN2, respectively) and two PMOS transistors (represented by PP1 and PP2, respectively), wherein the drain end of the PN1 is The drain terminals of the PP1 are connected to form a positive phase output terminal of the H-bridge power tube, and the drain terminal of the PN2 is connected to the drain terminal of the PP2 to form an inverting output terminal of the H-bridge power tube. The VPG_P signal and the VNG_P signal are the gate voltages of PN1 and PP1 of the positive-phase output of the H-bridge power transistor, and the VPG_N signal and the VNG_N signal are the gate voltages of PN2 and PP2 of the inverted output of the H-bridge power transistor, respectively.

 The output selection unit 5 includes eight branches:

The first branch and the second branch have the same structure, the first branch is connected between the Class AB drive unit 3 and the PP1, and the second branch is connected between the Class AB drive unit 3 and the PP2; The branch and the second branch each include a bias amplifying unit 51 and a switch S41. The bias amplifying unit 51 includes a biasing tube M1 and a biasing tube M2, and the biasing tubes M1 and M2 are PPs of the H-bridge power tube ( Including PP 1, PP2), PN (including PNl, PN2) provides gate terminal bias to ensure that PP and PN have static operating current when starting Class AB drive unit 3 for audio power amplifier processing to prevent crossover distortion; VB is the bias voltage of the biasing tubes M1, M2, and is supplied to the bias amplifying unit 51 through the current source II. For current, the current source 12 is used to prevent the VON1 signal or the VOP1 signal from flowing into the earth; the third branch and the fourth branch have the same structure, and the third branch is connected between the Class AB drive unit 3 and the PN1, The four branches are connected between the Class AB drive unit 3 and the PN2; the third branch and the fourth branch each comprise a switch S42;

 The fifth branch and the sixth branch have the same structure, the fifth branch is connected between the Class D modulation unit 4 and the PP1, and the sixth branch is connected between the Class D modulation unit 4 and the PP2; Both the branch road and the sixth branch include a switch S43;

 The seventh branch and the eighth branch have the same structure, the seventh branch is connected between the Class D modulation unit 4 and the PN1, and the eighth branch is connected between the Class D modulation unit 4 and the PN2; The seven branches and the eighth branch each include a switch S44.

 When the switch array unit 2 turns on the Class AB drive unit 3, the S-MOD control switch S41 and the switch S42 are turned on, the control switch S43 and the switch S44 are turned off; when the switch array unit 2 is turned on the Class D modulation unit 4, S_MOD The control switch S41 and the switch S42 are turned off, and the control switch S43 and the switch S44 are turned on.

 When the switch array unit 2 is turned on to turn on the Class AB drive unit 3, the principle that the output selection unit 5 processes the VON1 signal and the VOP1 signal output from the Class AB drive unit 3 is as follows: The output selection unit 5 outputs the Class AB drive unit 3 The VON1 signal is divided into two outputs, and one VON1 signal is amplified by the bias amplifying unit 51 of the first branch to obtain a VPG_N1 signal with a larger gain, and the VPG_N1 signal is output to the power output unit 6H bridge power tube. PP2 of the inverting output; another VON1 signal (ie, VNG_N1 signal) is output to the PN2 of the inverting output of the power supply unit 6H bridge power tube through the second branch; the above PP2 inverts the received VPG_N1 signal to obtain the inversion The VPG_N1 signal, the PN2 inverts the received VNG_N1 signal to obtain an inverted VNG N1 signal; the power output unit 6 superimposes the inverted VPG N1 signal and the inverted VNG_N1 signal to obtain an OUTN1 signal.

Similarly, the output selection unit 5 divides the VOP1 signal outputted by the Class AB drive unit 3 into two outputs, and one VOP1 signal is amplified by the bias amplification unit 51 of the first branch to obtain a larger gain set to the VPG-P1 signal. And output the VPG-P1 signal to the power output unit 6H bridge PP1 of the positive phase output of the power tube; another VOP1 signal (ie, VNG_P1 signal) is output to the PN1 of the positive phase output of the power output unit 6H bridge power tube through the second branch; the above VPP-P1 signal received by PP1 Inverting to obtain an inverted VPG_P1 signal, the PN1 inverting the received VG-P1 signal to obtain an inverted VNG_P1 signal; the power output unit 6 superimposing the inverted VPG_P1 signal and the inverted VNG_P1 signal to obtain an OUTP1 signal .

 When the switch array unit 2 is turned on to turn on the Class D modulation unit 4, the principle that the output selection unit 5 processes the VON2 signal and the VOP2 signal output from the Class D modulation unit 4 is as follows: The output selection unit 5 outputs the Class D modulation unit 4. The VON2 signal is divided into two outputs, one VON2 signal passes through the third branch to obtain the VPG-N2 signal, and the VPG-N2 signal is output to the PP2 of the inverting output end of the power output unit 6H bridge power tube; the other VON2 signal (ie VNG_N2) The signal is output to the PN2 of the inverting output terminal of the power supply unit 6H bridge power tube through the second branch; the PP2 inverts the received VPG_N2 signal to obtain the inverted VPG_N2 signal, and the PN2 reverses the received VNG_N2 signal. The phase obtains an inverted VNG_N2 signal; the power output unit 6 superimposes the inverted VPG_N2 signal and the inverted VNG_N2 signal to obtain an OUTN2 signal.

 Similarly, the output selection unit 5 divides the VOP2 signal outputted by the Class D modulation unit 4 into two outputs, and one VOP2 signal obtains a VPG_P2 signal through the third branch, and the VPG_P2 signal is output to the positive phase output of the power output unit 6H bridge power tube. PP1 of the other end; the other VOP2 signal (ie, VNG_P2 signal) is output to the PN1 of the positive phase output terminal of the power supply unit 6H bridge power tube through the second branch; the above PP1 inverts the received VPG_P2 signal to obtain the inverted VPG_P2 The signal, the PN1 inverts the received VNG-P2 signal to obtain an inverted VNG P2 signal; the power output unit 6 superimposes the inverted VPG-P2 signal and the inverted VNG_P2 signal to obtain an OUTP2 signal.

Preferably, since the VON2 signal or the VOP2 signal output by the Class D modulation unit 4 is a discrete signal, if the discrete signal is directly output to the H-bridge power tube, both the PN and the PP in the H-bridge power tube have large parasitics. Capacitance, therefore, in order to ensure a sufficient response speed, a driving circuit B1 composed of a plurality of inverter units is disposed in the third branch, and a driving circuit B2 composed of a plurality of inverter units is disposed in the fourth branch As shown in Figure 4-2, the inverter circuit included in the drive circuits B1 and B2 The number of elements can be determined based on the response speed requirement.

 Preferably, in order to prevent the VPG_N2 signal and the VNG-N2 signal from transitioning from a logic "low" potential to a "high" potential, since the PP2 and PN2 of the inverting output end of the H-bridge power tube are simultaneously turned on, an instantaneous high-current current is generated. The problem is that a dead zone unit is disposed in the third branch, and the VON2 signal or the VOP2 signal is sent to the driving circuit B1 after passing through the dead zone unit, as shown in FIG. 4-3. The dead zone unit in the embodiment of the present invention may It is implemented according to a circuit for implementing a dead zone unit in the prior art.

 In the embodiment of the present invention, not only the dead zone unit is set in the third branch, but also the dead zone unit is set in the fourth branch, and the VON2 signal or the VOP2 signal is sent to the driving circuit B2 after passing through the dead zone unit.

 Preferably, when the Class AB driving unit 3 in the audio power amplifier is selected for audio power amplifier processing, the entire audio power amplifier system is a continuous negative feedback loop, which is equivalent to an amplifier cascade of 2 to 3 stages, and the H-bridge power tube PP1 and PN1 of the positive phase output form a common source amplifier, or PP2 and PN2 of the inverting output terminal form a common source amplifier, and each has a large parasitic capacitance, and has a low frequency left at the VPG_N1 signal, the VNG-N1 signal, and the OUTP1 signal end. The Left-Half panel pole, the pole of the left half plane affects the stability of the closed loop of the audio power amplifier system; therefore, to ensure the stability of the closed loop of the entire audio power amplifier system, in Figure 4-1, Figure 4 above 2. In the circuit structure of Figure 4-3, the Miller capacitor CC1 is set between the gate and the drain of the PP, and the Miller capacitor CC2 is set between the gate and the drain of the PN, as shown in Figure 4-4. The circuit structure shown in Figure 4-5 and Figure 4-6; pushing the poles of the VPG_N1 signal and the VNG-N1 signal to a lower frequency, thereby improving the phase margin of the amplifier open loop (Phase Margin), and then ensuring the power amplifier system Closed-loop stability. The capacitance of the Miller capacitors CC1 and CC2 is determined according to the Class AB driving unit 3. Generally, the capacitance of the Miller capacitor CC1 is 0.1 to 0.2 times the capacitance of the PP gate terminal, and the capacitance of CC2 is the capacitance of the PN gate terminal. 0.1 to 0.2 times.

 The embodiment of the present invention further provides a method for implementing audio power amplifier mode switching, including: Step 1. The preamplifier unit of the audio power amplifier performs differential amplification processing on the received single-ended audio voltage signal to obtain two dual-ended differential signals. And output;

Step 2: The external logic control port of the audio power amplifier outputs a control signal to indicate that the switch array unit of the audio power amplifier turns on the Class AB driving unit or the Class D modulation unit; Step 3: The switch array unit turns on the audio power amplifier Class AB driving unit or the Class D modulation unit according to the control signal output by the external logic control port; and converts the differential signal output by the preamplifier unit into a a first differential signal or a second differential signal corresponding to the Class AB driving unit or the Class D modulation unit that is turned on;

 Step 4: When the switch array unit turns on the Class AB driving unit, the Class AB driving unit performs audio power amplifier processing on the first differential signal output by the switch array unit, and outputs the first after the audio power amplifier processing Differential signal

 Step 5: The Class D modulation unit performs audio power amplifier processing on the second differential signal output by the switch array unit when the switch array unit turns on the Class D modulation unit, and outputs the second after the audio power amplifier processing Differential signal

 Step 6. The output selection unit of the audio power amplifier is configured to perform amplification processing on the first differential signal outputted by the Class AB driving unit, and output the same; and output the second differential signal to the Class D modulation unit for processing and outputting;

 Step 7. The power output unit processes the signal output by the output selection unit and outputs the signal to the load.

 In the foregoing process step 2, the external logic control port of the audio power amplifier outputs a control signal, which specifically includes:

 When the power consumption corresponding to the function mode of the device where the audio power amplifier is located is higher than or equal to the set power consumption threshold, if the EMI sensitivity is lower than the set sensitive threshold, the external logic control port output is used for Instructing to turn on the control signal of the Class D modulation unit, if the EMI sensitivity is higher than or equal to the set sensitive value, outputting a control signal for instructing to turn on the Class AB driving unit through the external logic control port;

 When the power consumption corresponding to the function mode in which the device in which the audio power amplifier is currently located is lower than the power consumption threshold, a control signal for instructing the Class AB driving unit to be turned on is output through the external logic control port.

5 is a flowchart of performing audio power amplifier mode switching by using the above audio power amplifier according to an embodiment of the present invention, where the process includes the following steps: Step 500: The electronic system of the portable audio electronic product where the audio power amplifier is located acquires a power consumption parameter of the currently function mode.

 Step 501: The electronic system of the audio electronic product determines, according to the power consumption parameter, whether the power consumption required by the current function mode is higher than or equal to a set power consumption threshold (ie, whether the function mode has a low power consumption requirement), If otherwise, step 502 is performed, and if yes, step 504 is performed.

 Step 502: Output a control signal for instructing to turn on the Class AB driving unit 3, such as a high level signal or a logic bit 1, to the switch array unit 2 through the S_MOD, and then perform step 503.

 Step 503: The switch array unit 2 turns on the Class AB driving unit 3 according to the control signal sent by the S-MOD.

 Step 504: The electronic system determines whether the portable audio electronic product has a functional unit that is sensitive to EMI, and the functional unit is more sensitive to EMI than the set sensitive threshold. If yes, step 505 is performed, otherwise step 506 is performed. .

 Step 505: Determine whether the current function mode needs to enable a function unit that is sensitive to EMI, and if necessary, perform step 502, if otherwise, perform step 506.

 Step 506: Output a control signal for instructing to turn on the Class D modulation unit 4, such as a low level signal or a logic bit 0, to the switch array unit 2 through the S-MOD, and then perform step 507.

 Step 507: The switch array unit 2 turns on the Class D modulation unit 4 according to the control signal sent by the S_MOD.

The audio power amplifier in the embodiment of the invention integrates a functional unit for realizing the Class AB power amplifier and a functional unit for realizing the Class D power amplifier; the electronic system of the audio electronic product where the audio power amplifier is located is based on the current function of the electronic product The mode requires EMI and power consumption to send a control signal to the switch array unit through the S_MOD to indicate that the switch array unit is turned on to implement the functional unit of the Class AB amplifier or to turn on the functional unit of the Class D amplifier; thus, the audio is realized. The electronic product selects the corresponding audio power amplifier processing mode in different functional modes to meet the requirements of EMI and power consumption of different functions of the audio electronic product. Spirit and scope. Thus, if such modifications and variations of the present invention are within the scope of the present invention The present invention is also intended to cover such modifications and variations within the scope of the equivalents.

Claims

Rights request

An audio power amplifier, comprising a Class AB driving unit, a Class D modulation unit, and a power output unit, further comprising:

 a preamplifier unit, configured to differentially amplify the received single-ended audio voltage signal to obtain two dual-ended differential signals and output the same;

 An external logic control port, coupled to the switch array unit, for outputting a control signal to instruct the switch array unit to turn on the Class AB drive unit or the Class D modulation unit;

 a switch array unit, further connected to the preamplifier unit, configured to turn on a Class AB driving unit or a Class D modulation unit according to a control signal output by the external logic control port; and output the preamplifier unit Converting the differential signal into a first differential signal or a second differential signal corresponding to the turned-on Class AB driving unit or the Class D modulation unit;

 The Class AB driving unit is connected to the switch array unit, and configured to perform audio power amplifier processing on the first differential signal output by the switch array unit when the switch array unit turns on the Class AB driving unit, and Outputting a first differential signal after the audio power amplifier is processed;

 The Class D modulation unit is connected to the switch array unit, and configured to perform audio power amplifier processing on the second differential signal output by the switch array unit when the switch array unit turns on the Class D modulation unit. And outputting a second differential signal after the audio power amplifier processing;

 And an output selection unit, which is respectively connected to the Class AB driving unit and the Class D modulation unit, for performing amplification processing on the first differential signal output by the Class AB driving unit, and outputting; for outputting the Class D modulation unit The second differential signal is processed and output;

 The power output unit is connected to the output selection unit for processing a signal output by the output selection unit and outputting the signal to a load.

 2. The audio power amplifier according to claim 1, wherein the Class AB driving unit is specifically configured to: perform audio power amplifier processing on the first differential signal output by the switch array unit to obtain a first audio signal. And outputting the second audio signal;

The Class D modulation unit is specifically applied to: a second difference outputted by the switch array unit The sub-signal performs audio power amplifier processing to obtain a third audio signal and a fourth audio signal and outputs the same; the output selecting unit is specifically applied to: copy the first audio signal output by the Class AB driving unit to obtain two paths first Audio signal, and amplifying one of the first audio signals to obtain a fifth audio signal, and outputting a fifth audio signal and another first audio signal; for performing a second audio signal output by the Class AB driving unit Copying two second audio signals, and amplifying one of the second audio signals to obtain a sixth audio signal, and outputting a sixth audio signal and another second audio signal; and, for modulating the Class D The third audio signal and the fourth audio signal output by the unit are respectively copied, and the two third audio signals and the two fourth audio signals are output;

 The power output unit is specifically configured to: invert and superimpose the first audio signal and the fifth audio signal to obtain a seventh audio signal and output the signal to the load; and to use the second audio signal, The six audio signals are inverted and superimposed to obtain an eighth audio signal and output to the load; for inverting and superimposing the two third audio signals to obtain a ninth audio signal and outputting to the load; The two channels of the fourth audio signal are inverted and superimposed to obtain a tenth audio signal and output to the load.

 The audio power amplifier according to claim 2, wherein the external logic control port outputs a control signal, specifically:

 When the power consumption corresponding to the function mode of the device where the audio power amplifier is currently located is higher than or equal to the set power consumption threshold, if the EMI sensitivity is lower than the set sensitivity threshold, the port is controlled by the external logic. Outputting a control signal for indicating that the Class D modulation unit is turned on, and if the EMI sensitivity is higher than or equal to the set sensitive threshold, outputting a control signal for instructing to turn on the Class AB driving unit through the external logic control port;

 When the power consumption corresponding to the function mode in which the device in which the audio power amplifier is currently located is lower than the power consumption threshold, a control signal for instructing the Class AB driving unit to be turned on is output through the external logic control port.

The audio power amplifier according to claim 3, wherein the preamplifier unit comprises an operational amplifier, a first resistor R11, a second resistor R12, a third resistor R21, and a fourth resistor. R22, a fifth resistor R31 and a sixth resistor R32, the switch array unit includes a first switch S01, a second switch S02, a third switch S03, a fourth switch S04, a fifth switch S11, a sixth switch S12, and a seventh a switch S13 and an eighth switch S14, wherein:

 An operational amplifier for performing differential amplification processing on the single-ended audio voltage signal; the third resistor R21 and the first switch S01 are connected in series to form a first feedback circuit, and the first feedback circuit is connected to an input end of the operational amplifier Between the output and the output, providing feedback for the audio power amplifier processing of the Class D modulation unit;

 The third resistor R21, the fifth resistor R31 and the fifth switch S11 are connected in series to form a second feedback circuit, and the second feedback circuit is connected between the input end of the operational amplifier and the output end of the power output unit, and is used for The Class AB driving unit performs audio power amplifier processing to provide feedback;

 The positive output terminal of the operational amplifier is respectively connected to the third switch S03 and the seventh switch S13 to form a corresponding first output end and a second output end; the first output end is configured to output the difference for the Class D modulation unit An in-phase input signal in the signal; the second output is configured to output an in-phase input signal in the differential signal for the Class AB driving unit;

 The negative output terminal of the operational amplifier is respectively connected to the fourth switch S04 and the eighth switch S14 to form a corresponding third output end and a fourth output end; and the third output end is configured to output the difference for the Class D modulation unit An inverting input signal in the signal; the fourth output is configured to output an inverted input signal in the differential signal for the Class AB driving unit;

 The switch array unit turns off the fifth switch S11, the sixth switch S12, the seventh switch S13, and the eighth switch S14 by turning on the first switch S01, the second switch S02, the third switch S03, and the fourth switch S04. Turning on the Class D modulation unit; the switch array unit turns on the fifth switch S11, the sixth switch S12, and the first switch S01, the second switch S02, the third switch S03, and the fourth switch S04 Seven switches S13 and an eighth switch S14 are used to turn on the Class AB drive unit.

The audio power amplifier according to claim 4, wherein the power output unit is an H-bridge power tube, and the non-phase output terminal of the H-bridge power tube includes a first PMOS transistor and a first NMOS transistor, and a drain end of the first PMOS transistor is connected to a drain end of the first NMOS transistor; an inverting output end of the H-bridge power tube includes a second PMOS transistor and a second NMOS transistor, and the second a drain end of the PMOS transistor is connected to a drain end of the second NMOS transistor;

 The output selection unit includes eight branches, wherein:

 The first branch and the second branch have the same structure. The first branch is connected between the Class AB drive unit and the first PMOS transistor, and the second branch is connected between the Class AB drive unit and the second PMOS transistor. The first branch and the second branch each include an offset amplifying unit and a ninth switch S41, for performing amplification processing on the first audio signal to obtain a third audio signal;

 The third branch and the fourth branch have the same structure. The third branch is connected between the Class AB drive unit and the first NMOS transistor, and the fourth branch is connected to the Class AB drive unit and the second NMOS transistor. The third branch and the fourth branch each include a tenth switch S42;

 The fifth branch and the sixth branch have the same structure. The fifth branch is connected between the Class D modulation unit and the first PMOS tube, and the sixth branch is connected to the Class D modulation unit and the second PMOS tube. The fifth branch and the sixth branch each include an eleventh switch S43;

 The seventh branch and the eighth branch have the same structure. The seventh branch is connected between the Class D modulation unit and the first NMOS transistor, and the eighth branch is connected to the Class D modulation unit and the second NMOS transistor. The seventh branch and the eighth branch each include a twelfth switch S44;

 The external logic control port is further configured to control the ninth switch S41 and the tenth switch S42 to be turned on when the switch array unit turns on the Class AB driving unit, and control the eleventh switch S43 and the twelfth switch S44 is turned off; when the switch array unit turns on the Class D modulation unit, the ninth switch S41 and the tenth switch S42 are controlled to be turned off, and the eleventh switch S43 and the twelfth switch S44 are controlled to be turned on.

 The audio power amplifier according to claim 5, wherein the selection output unit performs amplification processing on the first audio signal of the one channel, specifically: passing the first audio signal through the first branch The path is amplified by the offset amplifying unit in the first branch to obtain a fifth audio signal; the selection output unit performs amplification processing on the second audio signal of the one of the channels, specifically: the second The audio signal passes through the second branch and is amplified by the bias amplifying unit in the second branch to obtain a sixth audio signal;

The power output unit obtains a seventh audio signal, specifically: a first PMOS transistor pair The fifth audio signal is inversely processed to obtain an inverted fifth audio signal; the first MOS tube inverts the other first audio signal to obtain an inverted first audio signal; and the inverted fifth audio And superimposing the signal on the inverted first audio signal to obtain the seventh audio signal;

 The power output unit obtains an eighth audio signal, specifically: the second PMOS tube performs inverse processing on the sixth audio signal to obtain an inverted sixth audio signal; and the second MOS tube pairs another second audio The signal is inversely processed to obtain an inverted second audio signal; and the inverted sixth audio signal is superimposed with the inverted second audio signal to obtain the eighth audio signal;

 The power output unit obtains a ninth audio signal, specifically: the first PMOS transistor performs inverse processing on one of the third audio signals to obtain an inverted third audio signal; and the first NMOS transistor performs another third audio signal. Inverting processing, obtaining an inverted third audio signal; superimposing the two inverting third audio signals to obtain the ninth audio signal;

 The power output unit obtains a tenth audio signal, specifically: the second PMOS tube inverts one of the fourth audio signals to obtain an inverted fourth audio signal; and the second NMOS tube performs the fourth fourth audio signal Inverting processing to obtain an inverted fourth audio signal; superimposing the two inverted fourth audio signals to obtain the tenth audio signal.

 The audio power amplifier according to claim 5, wherein the fifth branch and the sixth branch each comprise a first driving circuit composed of a plurality of inverters;

 The seventh branch and the eighth branch each include a second driving circuit composed of a plurality of inverters.

The audio power amplifier according to claim 7, wherein the fifth branch and the sixth branch each comprise a dead zone unit, and the dead zone unit is connected to the output of the Class D modulation unit. Between the first driving circuits;

 The seventh branch and the eighth branch each include a dead zone unit connected between the output of the Class D modulation unit and the second driving circuit.

The audio power amplifier according to any one of claims 5 to 8, wherein a gate end and a drain end of the first PMOS transistor are connected by a first Miller capacitance; and a gate end of the second PMOS transistor is The drain terminal is connected by the second Miller capacitor; the first Miller capacitor is the same as the second Miller capacitor; the gate end and the drain end of the first NMOS transistor are connected by a third Miller capacitor; Tube The gate terminal and the drain terminal are connected by a fourth Miller capacitance; the third Miller capacitance is the same as the fourth Miller capacitance.

 10. A method for implementing audio power amplifier mode switching, which is characterized by:

 The preamplifier unit of the audio power amplifier differentially amplifies the received single-ended audio voltage signal to obtain two double-ended differential signals and outputs the signals;

 The external logic control port of the audio power amplifier outputs a control signal to indicate that the switch array unit of the audio power amplifier is turned on by the Class AB driving unit or the Class D modulation unit;

 The switch array unit turns on the audio power amplifier Class AB driving unit or the Class D modulation unit according to a control signal output by the external logic control port; and converts the differential signal output by the preamplifier unit into a connection a first differential signal or a second differential signal corresponding to the Class AB driving unit or the Class D modulation unit;

 When the switch array unit turns on the Class AB driving unit, the Class AB driving unit performs audio power amplifier processing on the first differential signal output by the switch array unit, and outputs a first differential signal after the audio power amplifier processing; An output selection unit of the audio power amplifier amplifies the first differential signal output by the Class AB driving unit and outputs the signal to the power output unit, and the power output unit processes the signal output by the output selection unit and outputs the signal to the load ;

 When the switch array unit turns on the Class D modulation unit, the Class D modulation unit performs audio power amplifier processing on the second differential signal output by the switch array unit, and outputs a second differential signal after the audio power amplifier processing; An output selection unit of the audio power amplifier processes and outputs the second differential signal outputted by the Class D modulation unit, and the power output unit processes the signal output by the output selection unit and outputs the signal to the load.

 The method of claim 10, wherein the external logic control port of the audio power amplifier outputs a control signal, specifically:

When the power consumption corresponding to the function mode of the device where the audio power amplifier is currently located is higher than or equal to the set power consumption threshold, if the EMI sensitivity is lower than the set sensitive threshold, the external logic control port is used for output. The control signal indicating that the Class D modulation unit is turned on, if the EMI sensitivity is higher than or equal to the set sensitive threshold, the external logic control port output is used for indicating the connection. Control signal of the Class AB drive unit;

 When the power consumption corresponding to the function mode in which the device in which the audio power amplifier is currently located is lower than the power consumption threshold, a control signal for instructing the Class AB driving unit to be turned on is output through the external logic control port.