Class-d amplification system and power conversion circuit therein

Abstract

A class-D amplification system and a power conversion circuit therein. The class-D amplification system includes a class-D amplification circuit to convert an input signal into a switching control signal by a pulse width modulation manner, to control a plurality of switches to switch a first inductor and a second inductor to convert an input power to generate a positive output signal and a negative output signal respectively, which are complementary to each other, to drive a load; and a power conversion circuit to convert at least one of the positive output signal and the negative output signal to generate a direct current supply power as at least part of a power source of the class-D amplification circuit.

Description

Technical Field

[0001] This invention relates to Class D amplification systems, and more particularly to Class D amplification systems that provide power based on at least a common-mode voltage. The invention also relates to a power conversion circuit that provides power to a Class D amplification circuit based on at least a common-mode voltage. Background Technology

[0002] Figure 1 This illustrates a prior art Class D amplification system. This prior art Class D amplification system 100 includes a Class D amplification circuit 10 and a low-dropout power conversion circuit 30. The Class D amplification circuit 10 includes a signal processing circuit 11, a drive circuit 12, and a Class D power stage circuit 13. The signal processing circuit 11 converts an input signal IN in analog or digital form into a switch control signal SW using pulse width modulation. The drive circuit 12 generates a drive signal DRV based on the switch control signal SW to control the switching of the switch in the Class D power stage circuit 13, generating a positive output signal VOP and a negative output signal VON to drive a load 20. The input signal IN is, for example, an audio signal, and the load 20 is, for example, a speaker.

[0003] The low-dropout power conversion circuit 30 is used to convert the power supply PVDD to the power supply AVDD, so as to provide power for circuits such as signal processing circuit 11 and / or drive circuit 12.

[0004] However, when the voltage difference between power supply PVDD and power supply AVDD is large, the low dropout power conversion circuit 30 will cause great power loss.

[0005] Figure 2 This illustrates another prior art Class D amplification system. This prior art Class D amplification system 200 also includes a switching power conversion circuit 40, which first converts the power supply PVDD to the power supply AVPP in a switching step-down manner, and then the low-dropout power conversion circuit 30 converts the power supply AVPP back to the power supply AVDD, so as to provide power for circuits such as signal processing circuit 11 and / or drive circuit 12, thereby achieving higher power conversion efficiency.

[0006] However, the switching power conversion circuit 40 requires additional power conversion components, such as inductor L3, and a switch to switch inductor L3, which increases cost and circuit size.

[0007] In view of this, the present invention addresses the shortcomings of the prior art by proposing a novel Class D amplification system that can improve power conversion efficiency at a lower cost and with a smaller circuit size. Summary of the Invention

[0008] In one viewpoint, the present invention provides a Class D amplification system, comprising: a Class D amplification circuit for converting an input signal into a switching control signal via pulse width modulation, for controlling a plurality of switches to switch a first inductor and a second inductor to convert an input power supply to generate a complementary positive output signal and a negative output signal to drive a load; and a power conversion circuit for converting at least one of the positive output signal and the negative output signal to generate a DC power supply as at least a portion of the power supply for the Class D amplification circuit.

[0009] In one embodiment, the power conversion circuit includes an input selection circuit for selecting one of the positive output signal and the negative output signal as a relay power source based on their magnitudes, wherein the power conversion circuit generates the DC power supply based on the relay power source.

[0010] In one embodiment, the input selection circuit selects the signal with the higher voltage between the positive output signal and the negative output signal as the relay power supply.

[0011] In one embodiment, the input selection circuit includes a first diode and a second diode, which are connected in reverse series between the positive output signal and the negative output signal. The current-out terminal of the first diode and the current-out terminal of the second diode are coupled to the relay power supply. Thus, the first diode and the second diode are used to electrically connect the higher voltage of the positive output signal and the negative output signal to the relay power supply.

[0012] In one embodiment, the input selection circuit includes: a first switch and a second switch, which are connected in series between the positive output signal and the negative output signal; and a comparison control circuit for comparing the positive output signal and the negative output signal to generate a selection signal for controlling the first switch and the second switch, and electrically connecting the positive output signal with the higher voltage of the negative output signal to the relay power supply.

[0013] In one embodiment, the power conversion circuit further includes a first low drop-out linear regulator for generating the DC power supply based on the relay power supply.

[0014] In one embodiment, the power conversion circuit further includes a second low-dropout linear conversion circuit for generating the DC power supply based on the input power supply when the voltage of the relay power supply is below a threshold.

[0015] In one embodiment, the first inductor and a portion of a plurality of switches form a positive power stage, and the second inductor and another portion of a plurality of switches form a negative power stage, wherein both the positive and negative power stages correspond to a buck power stage circuit, a boost power stage circuit, or a buck-boost power stage circuit.

[0016] In one embodiment, when the input signal is indicated as a zero level, the voltage of the relay power supply is the common-mode level of the positive output signal and the negative output signal.

[0017] In one embodiment, the voltage of the relay power supply is the sum of half the amplitude of a differential-mode voltage and a common-mode voltage, wherein the differential-mode voltage corresponds to the difference between the positive output signal and the negative output signal, and the common-mode voltage corresponds to the common-mode level of the positive output signal and the negative output signal.

[0018] In one embodiment, the common-mode voltage is half the voltage of the input power supply.

[0019] In another viewpoint, the present invention provides a power conversion circuit for supplying power to a Class D amplifier circuit. The Class D amplifier circuit uses pulse width modulation to convert an input signal into a switching control signal to control multiple switches to switch a first inductor and a second inductor, thereby converting an input power supply to generate a positive output signal and a negative output signal to drive a load. The power conversion circuit includes: an input selection circuit for selecting one of the positive and negative output signals as a relay power supply based on their magnitudes; and a first low drop-out linear regulator for generating a DC power supply based on the relay power supply, serving as at least a portion of the power supply for the Class D amplifier circuit.

[0020] In one embodiment, the power conversion circuit further includes a second low-dropout linear conversion circuit for generating the DC power supply based on the input power supply when the voltage of the relay power supply is below a threshold.

[0021] The advantages of this invention are that it can improve light-load efficiency and reduce power consumption without requiring additional external components.

[0022] The following detailed description through specific embodiments will make it easier to understand the purpose, technical content, features and effects achieved by the present invention. Attached Figure Description

[0023] Figure 1 It is a Class D amplification system that is a prior art display.

[0024] Figure 2 It is a Class D amplification system that demonstrates another existing technology.

[0025] Figure 3 This is a circuit diagram of a Class D amplifier system according to an embodiment of the present invention.

[0026] Figure 4 This is a circuit diagram illustrating the power conversion circuit of a Class D amplifier system according to an embodiment of the present invention.

[0027] Figure 5 This is a circuit diagram showing the power conversion circuit of a Class D amplifier system according to another embodiment of the present invention.

[0028] Figure 6 This is a circuit diagram showing the power conversion circuit of a Class D amplifier system according to another embodiment of the present invention.

[0029] Figure 7 This is a circuit diagram showing the power conversion circuit of a Class D amplifier system according to another embodiment of the present invention.

[0030] Figures 8A to 8H The present invention provides an example of a buck converter, a boost converter, and a buck-boost converter according to an embodiment of the present invention.

[0031] Symbols in the picture

[0032] 10: Class D amplifier circuit

[0033] 11: Signal processing circuit

[0034] 12: Drive circuit

[0035] 13: Class D power stage circuit

[0036] 20: Load

[0037] 30: Low dropout power conversion circuit

[0038] 40: Switching power conversion circuit

[0039] 50, 60, 70: Power conversion circuit

[0040] 51, 61: Input selection circuit

[0041] 52: First low-dropout linear conversion circuit

[0042] 53: Second low-dropout linear conversion circuit

[0043] 100, 200, 3000: Class D amplification systems

[0044] 131: Positron Power Stage

[0045] 132: Negative Carrier Power Stage

[0046] 611: Comparison control circuit

[0047] AVCC: (Input) Power

[0048] AVDD: (DC power supply)

[0049] CP: Selection Signal

[0050] D1: First diode

[0051] D2: Second diode

[0052] DRV: Drive signal

[0053] IN: Input signal

[0054] L1: First Inductor

[0055] L2: Second inductor

[0056] L3: Inductor

[0057] LX1, LX3: First end

[0058] LX2, LX4: Second end

[0059] PVDD: (Input) Power Supply

[0060] Q1, Q2, Q3, Q4: Switches

[0061] Q11: First switch

[0062] Q12: Second switch

[0063] SW: Switch control signal

[0064] VM: Relay Power Supply

[0065] VON: Negative output signal

[0066] VOP: Positive output signal Detailed Implementation

[0067] The accompanying drawings in this invention are all schematic and are mainly intended to show the coupling relationship between various circuits and the relationship between various signal waveforms. The circuits, signal waveforms and frequencies are not drawn to scale.

[0068] Figure 3 This is a circuit diagram of a Class D amplifier system according to an embodiment of the present invention. Figure 3As shown, the Class D amplification system 3000 of the present invention includes a Class D amplification circuit 10 and a power conversion circuit 50. The Class D amplification circuit 10 is used to convert the input signal IN into a switching control signal SW by, for example, pulse width modulation, to control multiple switches Q1 to Q4 to switch the first inductor L1 and the second inductor L2 to convert the input power supply PVDD and generate complementary positive output signals VOP and negative output signals VON to drive the load 20.

[0069] Reference Figure 3 Specifically, in one embodiment, the Class D amplifier circuit 10 includes a signal processing circuit 11, a driving circuit 12, and a Class D power stage circuit 13. The signal processing circuit 11 converts the input signal IN in analog or digital form into a switching control signal SW using pulse width modulation. The driving circuit 12 generates a driving signal DRV based on the switching control signal SW, which controls the switching of multiple switches Q1 to Q4 in the Class D power stage circuit 13 to switch the first inductor L1 and the second inductor L2, thereby converting the input power supply PVDD to generate complementary positive output signals VOP and negative output signals VON to drive the load 20.

[0070] like Figure 3 As shown, switch Q1 is coupled between the input power supply PVDD and the first terminal LX1 of the first inductor L1, while switch Q2 is coupled between the ground potential and the first terminal LX1 of the first inductor L1. The drive signal DRV controls switches Q1 and Q2 to switch the first terminal LX1 of the first inductor L1 between the input power supply PVDD and the ground potential. Switch Q3 is coupled between the input power supply PVDD and the first terminal LX3 of the second inductor L2, while switch Q4 is coupled between the ground potential and the first terminal LX3 of the second inductor L2. The drive signal DRV controls switches Q3 and Q4 to switch the first terminal LX3 of the second inductor L2 between the input power supply PVDD and the ground potential. The positive output signal VOP at the second terminal LX2 of the first inductor L1 is related to the voltage at the first terminal LX1 of the first inductor L1, while the negative output signal VON at the second terminal LX4 of the second inductor L2 is related to the voltage at the first terminal LX3 of the second inductor L2. In one embodiment, the positive output signal VOP and the negative output signal VON are complementary in waveform to drive the load 20.

[0071] Please refer to the following: Figure 3 The first inductor L1, together with switches Q1 and Q2, forms a positive sub-power stage 131, and the second inductor L2, together with switches Q3 and Q4, forms a negative sub-power stage 132. Figures 8A to 8H This is an example of a buck converter, a boost converter, and a buck-boost converter according to an embodiment of the present invention. Please also refer to... Figure 3 and Figures 8A-8B In one embodiment, both the positive power stage 131 and the negative power stage 132 are, for example, simultaneously configured as buck power stage circuits. Please refer to... Figures 8C to 8D In another embodiment, the positive power stage 131 and the negative power stage 132 may both be simultaneously replaced to correspond to a boost-type power stage circuit. Please refer to... Figures 8E to 8H In another embodiment, the positive power stage 131 and the negative power stage 132 are, for example, simultaneously replaced to correspond to a buck-boost power stage circuit. The input signal IN is, for example, an audio signal, and the load 20 is, for example, a speaker. In one embodiment, the fundamental frequency component of the difference between the complementary positive output signal VOP and the negative output signal VON corresponds to the input signal IN. In one embodiment, the duty cycle of the switch control signal SW is related to the level of the input signal IN.

[0072] like Figure 3 As shown, the power conversion circuit 50 is coupled to the second terminal LX2 of the first inductor L1 and the second terminal LX4 of the second inductor L2, and is used to receive and convert at least one of the positive output signal VOP and the negative output signal VON to generate a DC power supply AVDD, which serves as at least a portion of the power supply for the Class D amplifier circuit 10. In one embodiment, the power conversion circuit 50, for example, converts the positive output signal VOP, or converts the negative output signal VON, or converts both the positive output signal VOP and the negative output signal VON to generate the DC power supply AVDD. Figure 3 As shown, the DC power supply AVDD serves as the power supply for signal processing circuit 11 and / or drive circuit 12. In one embodiment, the DC power supply AVDD serves as the power supply for drive circuit 12.

[0073] Figure 4 This is a circuit diagram illustrating the power conversion circuit 50 of a Class D amplifier system according to an embodiment of the present invention. Figure 4 As shown, the power conversion circuit 50 includes an input selection circuit 51 and a first low drop-out linear regulator 52. The input selection circuit 51 selects one of the positive output signal VOP and the negative output signal VON as the relay power supply VM based on their magnitudes. In one embodiment, the input selection circuit 51 selects the signal with the higher voltage between the positive output signal VOP and the negative output signal VON as the relay power supply VM. In one embodiment, the value of the higher voltage selected by the input selection circuit 51 is preferably greater than or equal to half of the input power supply PVDD. The first low drop-out linear regulator 52 generates a DC power supply AVDD based on the relay power supply VM. In one embodiment, the first low drop-out linear regulator 52 converts the relay power supply VM to the DC power supply AVDD in a linear conversion manner.

[0074] In one embodiment, when the input signal IN is indicated as zero level, the voltage of the relay power supply VM is the common-mode level of the positive output signal VOP and the negative output signal VON. In another embodiment, the voltage of the relay power supply VM is the sum of half the amplitude of the differential-mode voltage and the common-mode voltage, where the differential-mode voltage corresponds to the difference between the positive output signal VOP and the negative output signal VON, and the common-mode voltage corresponds to the common-mode level of the positive output signal VOP and the negative output signal VON. The amplitude of the differential-mode voltage is half the peak-to-peak value of the differential-mode voltage; in other words, half the amplitude of the differential-mode voltage corresponds to one-quarter of the peak-to-peak value of the differential-mode voltage. The common-mode level refers to the average level of the positive output signal VOP and the negative output signal VON. In one embodiment, the common-mode voltage is half the voltage of the input power supply PVDD.

[0075] Figure 5 This is a circuit diagram illustrating the power conversion circuit 50 of a Class D amplifier system according to a specific embodiment of the present invention. Figure 5 As shown, in this embodiment, the input selection circuit 51 includes a first diode D1 and a second diode D2, which are connected in series in reverse to each other between the positive output signal VOP and the negative output signal VON. The current outflow terminals of the first diode D1 and the second diode D2 are connected to the relay power supply VM. Thus, the first diode D1 and the second diode D2 are used to electrically connect the higher voltage of the positive output signal VOP and the negative output signal VON to the relay power supply VM.

[0076] Figure 6 This is a circuit diagram of the power conversion circuit 60 of a Class D amplification system according to another specific embodiment of the present invention. Figure 6 As shown, this embodiment is similar to Figure 5 The difference lies in that the input selection circuit 61 in this embodiment includes a first switch Q11, a second switch Q12, and a comparison control circuit 611. The first switch Q11 and the second switch Q12 are connected in series and coupled between the positive output signal VOP and the negative output signal VON. The comparison control circuit 611 compares the positive output signal VOP and the negative output signal VON to generate a selection signal CP, which controls the first switch Q11 and the second switch Q12 to electrically connect the signal with the higher voltage between the positive output signal VOP and the negative output signal VON to the relay power supply VM. It should be noted that the input selection circuit of this invention, in addition to... Figure 5 The diode embodiment shown and Figure 6 In addition to the switch embodiment shown, other feasible embodiments may also be used.

[0077] Figure 7 This is a circuit diagram showing the power conversion circuit 70 of a Class D amplifier system according to another embodiment of the present invention. Figure 7 As shown, this embodiment is similar to Figure 4 The difference in this embodiment is that the power conversion circuit 70 further includes a second low-dropout linear converter circuit 53, which generates a DC supply power supply AVDD based on the input power supply AVCC when the voltage of the relay power supply VM is below a threshold. Specifically, the second low-dropout linear converter circuit 53 can provide the DC supply power supply AVDD during the startup of the Class D amplifier circuit 10. In one embodiment, the input power supply AVCC is related to the input power supply PVDD, for example, they are equivalent, or a filter resistor with a low resistance value is electrically connected between the input power supply AVCC and the input power supply PVDD.

[0078] In one embodiment, the above-described Figure 3 The power conversion circuit 50 shown is integrated with a portion of the Class D amplifier circuit 10 (e.g., excluding the first inductor L1 and the second inductor L2, or further excluding the switches Q1 to Q4) into a single integrated circuit.

[0079] As described above, the present invention provides a Class D amplifier system that converts the output signal of the Class D amplifier circuit into a DC power supply AVDD through a power conversion circuit. Since the power stages of the Class D amplifier circuit itself are all switching power converters, the present invention can improve light-load efficiency and reduce power consumption without requiring additional external components.

[0080] The present invention has been described above with reference to preferred embodiments. However, the above description is only intended to facilitate understanding of the invention by those skilled in the art and is not intended to limit the broadest scope of the invention. The described embodiments are not limited to individual application and can also be used in combination. For example, two or more embodiments can be used in combination, and some components of one embodiment can be used to replace corresponding components in another embodiment. Furthermore, within the same spirit of the invention, those skilled in the art can conceive of various equivalent changes and combinations. For example, the phrase "processing or calculating based on a signal or generating an output result" in the present invention is not limited to the signal itself, but also includes, when necessary, performing voltage-to-current conversion, current-to-voltage conversion, and / or proportional conversion on the signal, and then processing or calculating based on the converted signal to generate an output result. Therefore, within the same spirit of the invention, those skilled in the art can conceive of various equivalent changes and combinations, and there are many combinations, which will not be listed here. Therefore, the scope of the present invention should cover the above and all other equivalent changes.

Claims

1. A class-D amplification system, comprising: a class-D amplification circuit for converting an input signal into a switching control signal by pulse width modulation to control a plurality of switches to switch a first inductor and a second inductor to convert an input power supply to generate a positive output signal and a negative output signal, respectively, to drive a load; and a power conversion circuit for converting at least one of the positive output signal and the negative output signal to generate a DC supply power as at least part of a power supply for the class-D amplification circuit; wherein the power conversion circuit includes an input selection circuit for selecting one of the positive output signal and the negative output signal as a relay power supply according to a magnitude of the positive output signal and the negative output signal, wherein the power conversion circuit generates the DC supply power according to the relay power supply; wherein the positive output signal and the negative output signal are complementary audio signals to each other.

2. The class D amplification system of claim 1, wherein, the first inductor and a part of the plurality of switches form a positive sub-power stage, and the second inductor and another part of the plurality of switches form a negative sub-power stage, wherein the positive sub-power stage and the negative sub-power stage both correspond to a step-down power stage circuit at the same time.

3. The class D amplification system of claim 1, wherein, the input selection circuit selects the one of the positive output signal and the negative output signal having a higher voltage as the relay power supply.

4. The class D amplification system of claim 3, wherein, the input selection circuit includes a first diode and a second diode coupled in anti-parallel to each other between the positive output signal and the negative output signal, and a current outflow end of the first diode and a current outflow end of the second diode are coupled to the relay power supply, whereby the first diode and the second diode electrically connect the one of the positive output signal and the negative output signal having the higher voltage to the relay power supply.

5. The class D amplification system of claim 3, wherein, the input selection circuit includes: a first switch and a second switch coupled in series to each other between the positive output signal and the negative output signal; a comparison control circuit for comparing the positive output signal and the negative output signal to generate a selection signal to control the first switch and the second switch to electrically connect the one of the positive output signal and the negative output signal having the higher voltage to the relay power supply.

6. The class D amplification system of any one of claims 1, 4 or 5, wherein, the power conversion circuit further includes a first low-dropout linear conversion circuit for generating the DC supply power according to the relay power supply.

7. The class D amplification system of claim 6, wherein, the power conversion circuit further includes a second low-dropout linear conversion circuit for generating the DC supply power according to the input power supply when a voltage of the relay power supply is lower than a threshold value.

8. The class D amplification system of claim 1, wherein, the first inductor and a part of the plurality of switches form a positive sub-power stage, and the second inductor and another part of the plurality of switches form a negative sub-power stage, wherein the positive sub-power stage and the negative sub-power stage both correspond to a step-up power stage circuit or a step-up / down power stage circuit at the same time.

9. The class D amplification system of claim 3, wherein, when the input signal is indicative of a zero level, a voltage of the relay power supply is a common mode level of the positive output signal and the negative output signal.

10. The class D amplification system of claim 3, wherein, a voltage of the relay power supply is a sum of one-half amplitude of a differential mode voltage and a common mode voltage, wherein the differential mode voltage corresponds to a difference between the positive output signal and the negative output signal, and wherein the common mode voltage corresponds to a common mode level of the positive output signal and the negative output signal.

11. The class D amplification system of claim 10, wherein, The common-mode voltage is 1 / 2 of the voltage of the input power supply.

12. A power conversion circuit for supplying power to a class-D amplifier circuit, the class-D amplifier circuit being configured to convert an input signal into a switching control signal by pulse width modulation, the switching control signal being configured to control a plurality of switches to switch a first inductor and a second inductor to convert an input power supply into a positive output signal and a negative output signal, respectively, to drive a load; the power conversion circuit comprising: an input selection circuit configured to select one of the positive output signal and the negative output signal as a relay power supply according to magnitudes of the positive output signal and the negative output signal; a first low-dropout linear conversion circuit configured to generate a direct current supply power according to the relay power supply as at least part of power supply for the class-D amplifier circuit; wherein, the positive output signal and the negative output signal are complementary audio signals.

13. The power conversion circuit of claim 12, wherein, The input selection circuit selects the one of the positive output signal and the negative output signal having a higher voltage as the relay power supply.

14. The power conversion circuit of claim 13, wherein, The input selection circuit includes a first diode and a second diode coupled in anti-parallel between the positive output signal and the negative output signal, and current flow outlets of the first diode and the second diode are coupled to the relay power supply, whereby the first diode and the second diode are configured to electrically connect the one of the positive output signal and the negative output signal having a higher voltage to the relay power supply.

15. The power conversion circuit of claim 13, wherein, The input selection circuit includes: a first switch and a second switch coupled in series between the positive output signal and the negative output signal; a comparison control circuit configured to compare the positive output signal and the negative output signal to generate a selection signal to control the first switch and the second switch to electrically connect the one of the positive output signal and the negative output signal having a higher voltage to the relay power supply.

16. The power conversion circuit of claim 12, wherein, The power conversion circuit further includes a second low-dropout linear conversion circuit configured to generate the direct current supply power according to the input power supply when a voltage of the relay power supply is lower than a threshold value.

17. The power conversion circuit of claim 12, wherein, The first inductor and a part of the plurality of switches form a positive sub-power stage, and the second inductor and another part of the plurality of switches form a negative sub-power stage, wherein the positive sub-power stage and the negative sub-power stage are both corresponding to a step-down power stage circuit at the same time.

18. The power conversion circuit of claim 13, wherein, When the input signal is indicative of a zero level, a voltage of the relay power supply is a common-mode level of the positive output signal and the negative output signal.

19. The power conversion circuit of claim 13, wherein, The voltage of the relay power supply is a sum of one half of an amplitude of a differential-mode voltage and a common-mode voltage, wherein the differential-mode voltage corresponds to a difference between the positive output signal and the negative output signal, and wherein the common-mode voltage corresponds to a common-mode level of the positive output signal and the negative output signal.

20. The power conversion circuit of claim 19, wherein, The common-mode voltage is 1 / 2 of the voltage of the input power supply.

Images