An audio power amplifier with adaptive boost control circuit

Abstract

The present invention discloses an audio power amplifier with an adaptive boost control circuit, which relates to the technical field of integrated circuit application. The audio power amplifier comprises a reference voltage generating circuit, a boost circuit, an audio power amplifier, a low-pass filter, a gain control circuit, an amplitude detection circuit, a logic processing circuit, a coding conversion circuit and a plurality of switches. Since a low-pass filter, a gain control circuit, an amplitude detection circuit, a logic processing circuit, a coding conversion circuit, a reference voltage generating circuit and a plurality of switches are added to a typical audio power amplifier with a boost circuit, the boost circuit can be dynamically controlled to be turned on and off and the output PVDD of the boost circuit can be dynamically adjusted through the low-pass filter, the gain control circuit, the amplitude detection circuit, the logic processing circuit, the coding conversion circuit, the reference voltage generating circuit and the plurality of switches, thereby improving the efficiency of the entire circuit and improving the battery life.

Description

Technical Field

[0001] The invention relates to the technical field of integrated circuit application, and in particular to an audio power amplifier with an adaptive boost control circuit. Background Art

[0002] Typical audio power amplifier with boost circuit such as Figure 1 As shown in the figure, the battery voltage (VBAT) is continuously turned on through the boost circuit to boost to PVDD to provide voltage for the audio power amplifier. In this way, when the output power of the audio power amplifier is small, the boost is turned on, and the boost circuit consumes current, resulting in low efficiency of the entire circuit. In actual audio applications, when the audio input signal amplitude is small, it is not necessary to turn on the boost circuit to ensure good linearity performance.

[0003] Since the higher the DC-DC boost voltage, the lower the efficiency of the entire circuit, automatically adjusting the DC-DC output voltage according to the power size will make the entire circuit more efficient, thereby extending the battery life. Therefore, dynamically controlling the boost on and off and dynamically adjusting the boost output PVDD can improve the efficiency of the entire circuit and increase the battery life. However, the current typical audio power amplifier with a boost circuit cannot dynamically control the boost circuit on and off and cannot dynamically adjust the boost circuit output PVDD. Therefore, the typical audio power amplifier with a boost circuit has the problem of low efficiency of the entire circuit and low battery life. Summary of the invention

[0004] The purpose of the present invention is to provide an audio power amplifier with an adaptive boost control circuit, which can dynamically control the on and off of the boost circuit and dynamically adjust the output PVDD of the boost circuit, thereby improving the efficiency of the entire circuit and increasing the battery life.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] An audio power amplifier with an adaptive boost control circuit comprises a reference voltage generating circuit, a boost circuit, an audio power amplifier, a low-pass filter, a gain control circuit, an amplitude detection circuit, a logic processing circuit, a coding conversion circuit and a plurality of switches;

[0007] The reference voltage generating circuit is connected to the plurality of switches respectively; the plurality of switches are connected to the boost circuit and the code conversion circuit; the boost circuit is connected to the audio power amplifier; the low-pass filter and the gain control circuit are connected to the audio power amplifier; the amplitude detection circuit is connected to the low-pass filter and the gain control circuit; the logic processing circuit is connected to the amplitude detection circuit, the code conversion circuit and the boost circuit respectively;

[0008] The boost circuit is used to boost the battery voltage to PVDD to provide power supply for the audio power amplifier; the audio power amplifier is used to convert the input audio signal into a PWM signal; the low-pass filter and the gain control circuit are used to convert the PWM signal into a sinusoidal signal and adjust the gain of the sinusoidal signal to obtain an output voltage within the amplitude detection range; the amplitude detection circuit is used to sample the amplitude of the output voltage, obtain the code corresponding to the output voltage, and determine whether the output voltage is less than a preset voltage according to the code corresponding to the output voltage; the logic processing circuit is used to convert the code corresponding to the output voltage into a thermometer code , and outputs a low level to the boost circuit when the output voltage is less than the preset voltage, and outputs a high level to the boost circuit when the output voltage is greater than the preset voltage; the low level is used to turn off the boost circuit; the high level is used to turn on the boost circuit; the encoding conversion circuit is used to encode the thermometer code into a control code; the control code has only a single bit of 1, and the remaining bits are all 0; the reference voltage generating circuit is used to generate multiple reference voltages; the multiple switches are used to select one reference voltage from the multiple reference voltages as a reference voltage to the boost circuit under the control of the control code; the reference voltage is used to adjust PVDD.

[0009] Optionally, a battery is also included;

[0010] The battery is connected to the boost circuit; the battery is used to provide the battery voltage to the boost circuit.

[0011] Optionally, the low-pass filter and gain control circuit specifically include a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a first capacitor, a second capacitor, a third capacitor and a first comparator;

[0012] The first output end of the audio power amplifier is connected to the first end of the first resistor; the second end of the first resistor is respectively connected to the first end of the first capacitor and the first end of the second resistor; the second end of the first capacitor is grounded; the second end of the second resistor is respectively connected to the first end of the third resistor, the first end of the second capacitor and the negative input end of the first comparator; the second end of the third resistor, the second end of the second capacitor and the output end of the first comparator are all connected to the amplitude detection circuit;

[0013] The second output end of the audio power amplifier is connected to the first end of the fourth resistor; the second end of the fourth resistor is respectively connected to the first end of the third capacitor and the first end of the fifth resistor; the second end of the third capacitor is grounded; the second end of the fifth resistor is respectively connected to the first end of the sixth resistor and the positive input end of the first comparator; the second end of the sixth resistor is grounded.

[0014] Optionally, the amplitude detection circuit specifically includes a plurality of seventh resistors and a plurality of second comparators;

[0015] A plurality of the seventh resistors are connected in series in sequence; a reference current is input from the first end of each of the seventh resistors and output from the second end of each of the seventh resistors in sequence; the second end of the third resistor, the second end of the second capacitor and the output end of the first comparator are all connected to the positive input end of each of the second comparators; the negative input end of each of the second comparators is respectively connected to two of the seventh resistors connected to each other; of the two seventh resistors connected to each other, the second end of the seventh resistor into which the reference current flows first and the first end of the seventh resistor into which the reference current flows later are both connected to the negative input end of one of the second comparators; the output end of each of the second comparators is connected to the logic processing circuit.

[0016] Optionally, the preset voltage is less than m times the battery voltage; wherein 0 <m<0.9。

[0017] Optionally, the number of the switches is equal to the number of the reference voltages.

[0018] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0019] The audio power amplifier with adaptive boost control circuit disclosed in the present invention adds a low-pass filter and a gain control circuit, an amplitude detection circuit, a logic processing circuit, a coding conversion circuit, a reference voltage generating circuit and a plurality of switches on the basis of a typical audio power amplifier with a boost circuit, thereby dynamically controlling the boost circuit to be turned on and off and dynamically adjusting the boost circuit output PVDD through the low-pass filter and the gain control circuit, the amplitude detection circuit, the logic processing circuit, the coding conversion circuit, the reference voltage generating circuit and the plurality of switches, thereby improving the efficiency of the entire circuit and increasing the battery life. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0021] Figure 1 This is a schematic diagram of a typical audio power amplifier with a boost circuit;

[0022] Figure 2 It is a structural diagram of an embodiment of an audio power amplifier with an adaptive boost control circuit of the present invention;

[0023] Figure 3 The schematic diagram of the coding corresponding to the coding conversion of the present invention;

[0024] Figure 4 It is a schematic diagram of the amplitude detection circuit of the present invention;

[0025] Figure 5 is a schematic diagram of a logic processing circuit of the present invention;

[0026] Figure 6 It is a timing diagram of the logic processing circuit of the present invention;

[0027] Figure 7 Schematic diagram of a reference voltage generating circuit of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The purpose of the present invention is to provide an audio power amplifier with an adaptive boost control circuit, which can dynamically control the on and off of the boost circuit and dynamically adjust the output PVDD of the boost circuit, thereby improving the efficiency of the entire circuit and increasing the battery life.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Figure 2 FIG. 1 is a structural diagram of an embodiment of an audio power amplifier with an adaptive boost control circuit according to the present invention. Figure 2, the audio power amplifier with an adaptive boost control circuit includes a reference voltage generation circuit 101, a boost circuit 102, an audio power amplifier 103, a low-pass filter, a gain control circuit 104, an amplitude detection circuit 105, a logic processing circuit 106, an encoding conversion circuit 107, and a plurality of switches S0 to Sn-1.

[0032] The reference voltage generation circuit 101 is respectively connected to the plurality of switches S0 to Sn-1; the plurality of switches S0 to Sn-1 are all connected to the boost circuit 102 and the encoding conversion circuit 107; the boost circuit 102 is connected to the audio power amplifier 103; the low-pass filter and the gain control circuit 104 are connected to the audio power amplifier 103; the amplitude detection circuit 105 is connected to the low-pass filter and the gain control circuit 104; the logic processing circuit 106 is respectively connected to the amplitude detection circuit 105, the encoding conversion circuit 107, and the boost circuit 102.

[0033] The boost circuit 102 is used to boost the battery voltage VBAT to PVDD to provide a power supply for the audio power amplifier 103; the audio power amplifier 103 is used to convert the input audio signal into a PWM signal; the low-pass filter and the gain control circuit 104 are used to convert the PWM signal into a sine signal and adjust the gain of the sine signal to obtain an output voltage Vo within the amplitude detection range; the amplitude detection circuit 105 is used to sample the amplitude of the output voltage Vo to obtain an encoding C[N-1:0] corresponding to the output voltage Vo, and determine whether the output voltage Vo is less than a preset voltage V1 according to the encoding C[N-1:0] corresponding to the output voltage Vo; the preset voltage V1 is less than m times the battery voltage VBAT; where 0 < m < 0.9; the logic processing circuit 106 is used to convert the encoding C[N-1:0] corresponding to the output voltage Vo into a thermometer code D[N-1:0], and output a low level EN = 0 to the boost circuit 102 when the output voltage Vo is less than the preset voltage V1, and output a high level EN = 1 to the boost circuit 102 when the output voltage Vo is greater than the preset voltage V1; the low level is used to turn off the boost circuit 102; the high level is used to turn on the boost circuit 102; the encoding conversion circuit 107 is used to encode the thermometer code D[N-1:0] into a control code T[N-1:0]; only one bit of the control code T[N-1:0] is 1, and the remaining bits are all 0, so that only one of the voltages is selected as the reference voltage when controlling S0 to Sn-1, such as Figure 3As shown, the coding principle is to ensure that only one of the switches S0~Sn-1 is turned on at the same time; the reference voltage generating circuit 101 is used to generate multiple reference voltages Vr1~Vrn; the number of reference voltages is equal to the number of switches; multiple switches S0~Sn-1 are used to select a reference voltage from multiple reference voltages Vr1~Vrn as a reference voltage for the boost circuit 102 under the control of the control code T[N-1:0]; the reference voltage is used to adjust PVDD.

[0034] The low-pass filter and gain control circuit 104 specifically includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a first capacitor C1, a second capacitor C2, a third capacitor C3 and a first comparator EA1. Figure 2 shown.

[0035] The first output end of the audio power amplifier 103 is connected to the first end of the first resistor R1; the second end of the first resistor R1 is respectively connected to the first end of the first capacitor C1 and the first end of the second resistor R2; the second end of the first capacitor C1 is grounded; the second end of the second resistor R2 is respectively connected to the first end of the third resistor R3, the first end of the second capacitor C2 and the negative input end of the first comparator EA1; the second end of the third resistor R3, the second end of the second capacitor C2 and the output end of the first comparator EA1 are all connected to the amplitude detection circuit 105.

[0036] The second output end of the audio power amplifier 103 is connected to the first end of the fourth resistor R4; the second end of the fourth resistor R4 is respectively connected to the first end of the third capacitor C3 and the first end of the fifth resistor R5; the second end of the third capacitor C3 is grounded; the second end of the fifth resistor R5 is respectively connected to the first end of the sixth resistor R6 and the positive input end of the first comparator EA1; the second end of the sixth resistor R6 is grounded.

[0037] The amplitude detection circuit 105 specifically includes a plurality of seventh resistors R7 and a plurality of second comparators EA2, such as Figure 4 shown.

[0038] A plurality of seventh resistors R7 are connected in series in sequence; a reference current Iref1 is input from the first end of each seventh resistor R7 in sequence and output from the second end of each seventh resistor R7; the second end of the third resistor R3, the second end of the second capacitor C2 and the output end of the first comparator EA1 are all connected to the positive input end of each second comparator EA2; the negative input end of each second comparator EA2 is respectively connected to two seventh resistors R7 connected to each other (except the second comparator EA2 connected to the first end of the first seventh resistor R7); of the two seventh resistors R7 connected to each other, the second end of the seventh resistor R7 into which the reference current Iref1 flows first and the first end of the seventh resistor R7 into which the reference current Iref1 flows later are both connected to the negative input end of a second comparator EA2; the output end of each second comparator EA2 is connected to the logic processing circuit 106; wherein the negative input end of the second comparator EA2 connected to the first end of the first seventh resistor R7 is connected to the first end of the first seventh resistor R7, not to the two seventh resistors R7 connected to each other, such as Figure 4 As shown; the first seventh resistor R7 is the first seventh resistor into which the reference current Iref1 flows.

[0039] The amplitude detection circuit 105 detects the amplitude of the output of the low-pass filter and the gain control circuit 104, and then determines the amplitude of the power amplifier output. Figure 4 In the figure, V1 is fed to the negative electrode of the first second comparator EA2, and the output is C[0]. V2 is fed to the negative electrode of the second second comparator EA2, and the output is C[1]. Similarly, Vn is fed to the negative electrode of the nth comparator, and the output is C[n-1].

[0040] The audio power amplifier with adaptive boost control circuit also includes a battery; the battery is connected to the boost circuit 102 ; the battery is used to provide a battery voltage VBAT for the boost circuit 102 .

[0041] In the audio power amplifier with adaptive boost control circuit, when the input audio signal is small, the output Vo of the low-pass filter and gain control circuit 104 is less than the preset voltage V1, the logic processing circuit 106 outputs EN=0, EN is low level, and the boost circuit 102 is turned off; when the input audio signal is large, Vo>V1, the logic processing circuit 106 outputs EN=1, EN is high level, and the boost circuit 102 is turned on. The amplitude detection circuit 105 samples the Vo amplitude and outputs the corresponding code C[N-1:0], C[N-1:0] outputs D[N-1:0] through the logic processing circuit 106, and then outputs T[N-1:0] through the code conversion circuit 107 to control the switches S0~Sn-1, select the reference voltages Vr1~Vrn to control the corresponding output voltage PVDD, so as to achieve the function of dynamically controlling the PVDD voltage. The dynamic control of the output voltage PVDD can improve the efficiency of the entire circuit and improve the battery life.

[0042] Among them, C[0] output by the second comparator EA2 can determine whether it is less than V1, as Figure 4 shown. V1 < m * VBAT (0 < m < 0.9, VBAT is the battery voltage), and m is selected as needed, and a small amplitude can be determined.

[0043] The logic processing circuit 106 is as Figure 5 shown, and the timing diagram of the logic processing circuit is as Figure 6 shown. C[N - 1:0] output by the amplitude detection circuit 105 is input to the logic processing circuit 106 from Figure 5 IN[N - 1:0] therein, and D[N - 1:0] is output from the logic processing circuit 106 from Figure 5 OUT[N - 1:0] therein. The functions implemented by the logic processing circuit 106 are as Figure 5 and Figure 6 shown. When IN is at a high level, OUT is at a high level; when IN is at a low level, OUT will become low after a delay of Td.

[0044] The reference voltage generation circuit 101 is used to generate a reference voltage to supply the boost circuit 102, and the switches S0 to Sn - 1 select one of the voltages to supply to the boost circuit 102. The reference voltage generation circuit 101 is as Figure 7 shown, Figure 7 wherein, Iref2 represents the reference current of the reference voltage generation circuit, Vr1 to Vrn are not equal, and R1 to Rn can be equal or not equal. Vr1 = Iref2 * R8, Vr2 = Iref2 * (R8 + R9)........ Vrn = Iref2 * (R8 + R9 +..... + Rn).

[0045] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other.

[0046] In this article, specific examples are used to elaborate on the principles and implementation manners of the present invention. The descriptions of the above embodiments are only used to help understand the core idea of the present invention; at the same time, for those of ordinary skill in the art, based on the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. An audio power amplifier with an adaptive boost control circuit, characterized in that: It includes a reference voltage generating circuit, a boosting circuit, an audio power amplifier, a low-pass filter, a gain control circuit, an amplitude detection circuit, a logic processing circuit, a coding conversion circuit and a plurality of switches, and also includes a battery; The reference voltage generating circuit is connected to the plurality of switches respectively; the plurality of switches are connected to the boost circuit and the code conversion circuit; the boost circuit is connected to the audio power amplifier; the low-pass filter and the gain control circuit are connected to the audio power amplifier; the amplitude detection circuit is connected to the low-pass filter and the gain control circuit; the logic processing circuit is connected to the amplitude detection circuit, the code conversion circuit and the boost circuit respectively; The boost circuit is used to boost the battery voltage to PVDD to provide power supply for the audio power amplifier; the audio power amplifier is used to convert the input audio signal into a PWM signal; the low-pass filter and the gain control circuit are used to convert the PWM signal into a sinusoidal signal, and adjust the gain of the sinusoidal signal to obtain an output voltage within the amplitude detection range; the amplitude detection circuit is used to sample the amplitude of the output voltage, obtain the code corresponding to the output voltage, and determine whether the output voltage is less than the preset voltage according to the code corresponding to the output voltage; the logic processing circuit is used to convert the code corresponding to the output voltage into a thermometer code, and output a low level to the boost circuit when the output voltage is less than the preset voltage, and output a high level to the boost circuit when the output voltage is greater than the preset voltage; the low level is used to turn off the boost circuit; the high level is used to turn on the boost circuit; the code conversion circuit is used to encode the thermometer code into a control code; the control code has only a single bit that is 1, and the remaining bits are all 0; the reference voltage generation circuit is used to generate multiple reference voltages; The plurality of switches are used to select one reference voltage from the plurality of reference voltages as a reference voltage for the boost circuit under the control of the control code; The reference voltage is used to adjust PVDD; The battery is connected to the boost circuit; the battery is used to provide the battery voltage to the boost circuit; The low-pass filter and gain control circuit specifically include a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a first capacitor, a second capacitor, a third capacitor and a first comparator; The first output end of the audio power amplifier is connected to the first end of the first resistor; the second end of the first resistor is respectively connected to the first end of the first capacitor and the first end of the second resistor; the second end of the first capacitor is grounded; the second end of the second resistor is respectively connected to the first end of the third resistor, the first end of the second capacitor and the negative input end of the first comparator; the second end of the third resistor, the second end of the second capacitor and the output end of the first comparator are all connected to the amplitude detection circuit; The second output end of the audio power amplifier is connected to the first end of the fourth resistor; the second end of the fourth resistor is respectively connected to the first end of the third capacitor and the first end of the fifth resistor; the second end of the third capacitor is grounded; the second end of the fifth resistor is respectively connected to the first end of the sixth resistor and the positive input end of the first comparator; the second end of the sixth resistor is grounded.

2. The audio power amplifier with adaptive boost control circuit according to claim 1, characterized in that: The amplitude detection circuit specifically includes a plurality of seventh resistors and a plurality of second comparators; A plurality of the seventh resistors are connected in series in sequence; a reference current is input from the first end of each of the seventh resistors and output from the second end of each of the seventh resistors in sequence; the second end of the third resistor, the second end of the second capacitor and the output end of the first comparator are all connected to the positive input end of each of the second comparators; the negative input end of each of the second comparators is respectively connected to two of the seventh resistors connected to each other; of the two seventh resistors connected to each other, the second end of the seventh resistor into which the reference current flows first and the first end of the seventh resistor into which the reference current flows later are both connected to the negative input end of one of the second comparators; the output end of each of the second comparators is connected to the logic processing circuit.

3. The audio power amplifier with adaptive boost control circuit according to claim 1, characterized in that: The preset voltage is less than m times the battery voltage; wherein, 0 <m<0.9。 4. The audio power amplifier with adaptive boost control circuit according to claim 1, characterized in that: The number of the switches is equal to the number of the reference voltages.

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