On-chip inductor with audio earphone amplifier

Abstract

A single integrated circuit (9) may include: a signal path configured to receive an input signal (V) IN Generate output signal (V) OUT ), wherein the signal path includes a signal configured to drive the output signal (V). OUT The amplifier (16); a DC-DC power converter (10) having a power inductor integrated in a single integrated circuit (9) and configured to generate a power supply voltage (V) from the source voltage to the amplifier. SUPPLY ); and a control circuit for controlling the operation of the converter switch of the DC-DC power converter (10) so that the power supply voltage (V SUPPLY Tracking input signal (V) IN ) and output signal (V OUT At least one of them.

Description

Technical Field

[0001] This disclosure generally relates to circuitry for audio devices, including but not limited to personal audio devices such as cordless phones and media players, and more specifically, to systems and methods relating to on-chip inductors having audio headphone amplifiers. Background Technology

[0002] Mobile devices, including cordless phones such as mobile / cellular phones, cordless phones, MP3 players, and other consumer audio devices, are widely used. Such mobile devices may include circuitry for driving transducers, including but not limited to headphones, speakers, linear resonant actuators or other vibration actuators, and / or any other suitable transducers.

[0003] In many audio systems, a linear amplifier can drive a transducer, and such a linear amplifier can be powered by a variable supply voltage that tracks the envelope of the output signal driven by the linear amplifier to the transducer. For example, a power supply for implementing such a variable supply voltage can include a buck converter or other switch-mode power converter, wherein such switch-mode power converters include off-chip power inductors. However, a drawback of many implementations of such topologies is that the switch-mode power converter cannot switch with sufficient bandwidth to effectively track the output signal driven by the linear amplifier across the entire audio bandwidth. Summary of the Invention

[0004] Based on the teachings of this disclosure, one or more disadvantages and problems associated with existing methods of implementing output signal envelope tracking power supplies can be reduced or eliminated.

[0005] According to embodiments of the present disclosure, a single integrated circuit may include a signal path configured to generate an output signal from an input signal, wherein the signal path includes an amplifier configured to drive the output signal; a DC-DC power converter having a power inductor integrated in the single integrated circuit and configured to generate a power supply voltage from a source voltage to the amplifier; and control circuitry for controlling the operation of a converter switch of the DC-DC power converter such that the power supply voltage tracks at least one of the input signal and the output signal.

[0006] According to embodiments of the present disclosure, a method may include generating an output signal from an input signal in a signal path within a single integrated circuit, wherein the signal path includes an amplifier configured to drive the output signal, a power supply voltage generated to the amplifier from a source voltage to a DC-DC power converter, wherein the DC-DC power converter has a power inductor integrated in the single integrated circuit, and operation of a converter switch of the DC-DC power converter controlled by control circuitry such that the power supply voltage tracks at least one of the input signal and the output signal.

[0007] The technical advantages of this disclosure will be apparent to those skilled in the art from the accompanying drawings, description, and claims included herein. The objects and advantages of the embodiments will be realized and achieved, at least by means of the elements, features, and combinations particularly pointed out in the claims.

[0008] It should be understood that the foregoing general description and the following detailed description are illustrative and not intended to limit the scope of the claims set forth in this disclosure. Attached Figure Description

[0009] A more complete understanding of this embodiment and its advantages can be obtained by referring to the following description in conjunction with the accompanying drawings, in which similar reference numerals denote similar features, and wherein:

[0010] Figure 1 This is an illustration of an exemplary personal audio device according to embodiments of the present disclosure;

[0011] Figure 2 This is a block diagram of selected components of an exemplary audio integrated circuit in a personal audio device according to embodiments of the present disclosure; and

[0012] Figure 3 This is a circuit diagram of selected components of an exemplary switch-mode power supply according to embodiments of the present disclosure. Detailed Implementation

[0013] Figure 1 This is an illustration of an exemplary mobile device 1 according to an embodiment of the present disclosure. Figure 1 A mobile device 1 is depicted that is coupled to a headset 3 in the form of a pair of earphone speakers 8A and 8B. Figure 1 The earphone 3 depicted is merely an example, and it is understood that it can be connected to various audio transducers for use with the mobile device 1, including but not limited to headphones, earbuds, in-ear headphones, and external speakers. The plug 4 provides electrical terminals for connecting the earphone 3 to the mobile device 1. The mobile device 1 may provide a display to the user and receive user input using a touchscreen 2, or alternatively, a standard liquid crystal display (LCD) may be combined with various buttons, sliders, and / or dials disposed on the surface and / or sides of the mobile device 1. Also... Figure 1 As shown, the mobile device 1 may include an audio integrated circuit (IC) 9 for generating analog audio signals to be transmitted to the headphones 3, the speaker 7, and / or another audio transducer.

[0014] Figure 2 A block diagram of selected components of an exemplary audio IC 9 of a personal audio device according to an embodiment of the present disclosure is shown. Figure 2 As shown, the microcontroller core 18 can provide a digital audio input signal DIG_IN to the digital-to-analog converter (DAC) 14, which can then convert the digital audio input signal into an analog signal V. IN DAC 14 can provide an analog signal V to amplifier 16. IN Amplifier 16 can amplify or attenuate the audio input signal V. IN To provide differential audio output signal V OUT The differential audio output signal V OUT It can operate speakers, headphone transducers, line-level signal outputs, and / or other suitable outputs. In some embodiments, DAC 14 may be an integrated component of amplifier 16. Power supply 10 can provide power rail inputs to the microcontroller core 18, DAC 14, and / or other components of audio IC 9. In some embodiments, power supply 10 may include a switch-mode power converter, as described in more detail below. Although Figure 1 and Figure 2 While the audio IC 9 resides in personal audio devices, the systems and methods described herein can also be applied to electrical and electronic systems and devices beyond personal audio devices, including audio systems used in larger computing devices, automobiles, buildings, or other structures. Furthermore, the systems and methods described herein are not limited to mobile audio devices and can also be used in video game controllers, touchscreens, automobiles, and any other devices requiring audio and / or haptic output.

[0015] Figure 3 This is a circuit diagram of selected components of an exemplary switch-mode power supply 10 according to embodiments of the present disclosure. In some embodiments, Figure 3 The switch-mode power supply 10 shown can be used to implement Figure 2 Switching mode power supply 10.

[0016] like Figure 3 As shown, the switch-mode power supply 10 can be implemented as a buck power converter, including a battery 72, a power inductor 78, converter switches 74 and 76, a buck capacitor 80, a level detector 84, a bypass switch 90, and a switch control circuit 86. In operation, the level detector 84 can receive the digital audio input signal DIG_IN and the audio output signal V. OUTand / or indicate audio output signal V OUT Another signal, and based on the detected signal level and / or the time rate of change of such detected signal level (e.g., the slope of such detected signal level), the switch control circuit 86 can cyclically switch the converter switches 74 and 76 to generate a battery voltage V on the buck capacitor 80 that is less than that on the battery 72. BAT power supply voltage V SUPPLY This type of power supply voltage V SUPPLY It is the minimum amount with sufficient margin to ensure linear and accurate operation of the current DAC 14 (e.g., a Class H amplifier). For example, the switch control circuit 86 can change one or both of the switching frequency and duty cycle of the switch-mode power supply 10 to generate the power supply voltage V. SUPPLY .

[0017] The current source integrated into DAC 14 may require a sufficient voltage drop across its terminals for accurate operation; this sufficient voltage drop can also be referred to as voltage margin. To create sufficient voltage margin while minimizing power consumption, the switch-mode power supply 10 can track the output signal V. OUT (For example, the output signal V can be indicated by tracking) OUT The digital audio input signal DIG_IN is used to generate a power supply voltage V sufficient to allow linear and accurate operation of the current-mode DAC 14. SUPPLY At the same time, the power supply voltage V SUPPLY Keep it as small as possible. The amount of headroom generated by the switch-mode power supply 10 can be optimized for efficiency or audio accuracy, and such optimization can vary dynamically, for example, based on project materials, volume control settings, ambient noise, and / or noise cancellation settings.

[0018] In this implementation, some or all of the components of the audio IC 9, including the power inductor 78, other components of the switch-mode power supply 10, and the amplifier 16, can be formed on a single integrated circuit die. Integrating the power inductor 78 with the other components of the switch-mode power supply 10 and the amplifier 16 on a single integrated circuit die enables a fast switching frequency for the switch-mode power supply 10, which can adjust the supply voltage V. SUPPLY Capable of tracking the audio output signal V across the entire audio bandwidth OUT For use in controlling power supply voltage V SUPPLY For even faster loop response, the switch control circuit 86 can be configured to operate the switch-mode power supply 10 in a discontinuous conduction mode (e.g., in a mode where the current through the power inductor 78 is zero during a period of the switching cycle of the switch-mode power supply 10).

[0019] Forming some or all of the audio ICs 9, including the power inductor 78, other components of the switch-mode power supply 10, and the amplifier 16, on a single integrated circuit die may have one or more advantages. For example, using a single integrated circuit die, the switch-mode power supply 10 can operate at switching frequencies of 10 MHz and above, including 20 MHz or higher. At a switching frequency of 20 MHz, the switch-mode power supply 10 can effectively track the 20 kHz audio signal amplified by the amplifier 16, enabling high levels of power efficiency and sufficient headroom and low audio distortion.

[0020] like Figure 3 As shown, in some embodiments, the switch control circuit 86 can activate (e.g., turn on, start, close) the bypass switch 90 to switch the battery voltage V. BAT Bypass to power supply voltage V SUPPLY For example, when the switching frequency of the switch-mode power supply 10 is insufficient to track the audio output signal V. OUT Such bypassing may occur when the signal frequency is [unspecified]. As another example, if the audio output signal V [unspecified]... OUT The amplitude is close to the battery voltage V. BAT Then the switch control circuit 86 can activate the bypass switch 90 to maximize the converter efficiency.

[0021] like Figure 3 As shown, the switch control circuit 86 can operate in feedforward mode (e.g., based on the digital audio input signal DIG_IN) and feedback mode (e.g., based on the output signal V). OUT The switching frequencies and / or duty cycles of converter switches 74 and 76, or combinations thereof, and the operation of bypass switch 90 are controlled. For example, in some embodiments, a hybrid approach may be used, wherein the switching frequencies of converter switches 74 and 76 can be determined based on signal power estimation using feedforward operation, and based on supply voltage V using feedback operation. SUPPLY The duty cycle is controlled by comparing it with a reference voltage. As another example, in other embodiments, a feedback operation can be used to control the duty cycle until a duty cycle limit is used, and then once this duty cycle limit is reached, a feedforward operation can be used to control the switching frequency of converter switches 74 and 76.

[0022] As used herein, when two or more elements are referred to as being “coupled” to each other, the term indicates that such two or more elements are in electronic or mechanical communication, whether, as applicable, indirect or direct, with or without intermediate elements.

[0023] This disclosure covers all changes, substitutions, variations, alterations, and modifications to the exemplary embodiments herein that will be understood by those skilled in the art. Similarly, where appropriate, the appended claims cover all changes, substitutions, variations, alterations, and modifications to the exemplary embodiments herein that will be understood by those skilled in the art. Furthermore, references in the appended claims to a device or system or a component of a device or system that are adapted, arranged, capable, configured, enabled, operable, or effective in performing a particular function cover that device, system, or component, whether or not it or that particular function is activated, switched on, or unlocked, provided that the device, system, or component is so adapted, arranged, capable, configured, enabled, operable, or effective. Therefore, modifications, additions, or omissions can be made to the systems, devices, and methods described herein without departing from the scope of this disclosure. For example, components of a system and device may be integrated or separated. Furthermore, the operation of the systems and devices disclosed herein may be performed by more, fewer, or other components, and the described methods may include more, fewer, or other steps. Furthermore, the steps may be performed in any suitable order. As used herein, “each” means each member of a set or each member of a subset of a set.

[0024] Although exemplary embodiments are shown in the accompanying drawings and described below, the principles of this disclosure can be implemented using any number of techniques, whether currently known or not. This disclosure should not be limited in any way to the exemplary embodiments and techniques shown in the drawings and described above.

[0025] Unless otherwise specified, the items depicted in the accompanying drawings are not necessarily drawn to scale.

[0026] All examples and conditional language cited herein are intended for pedagogical purposes to aid the reader in understanding the content and concepts of this disclosure contributed by the inventors to advance the art, and are not to be construed as being limited by the examples and conditions described herein. Although embodiments of this disclosure have been described in detail, it should be understood that various changes, substitutions, and modifications can be made thereto without departing from the spirit and scope of this disclosure.

[0027] While specific advantages have been listed above, various embodiments may include some, none, or all of the listed advantages. Furthermore, other technical advantages may become apparent to those skilled in the art after reading the foregoing figures and description.

[0028] In order to help the Patent Office and any reader of any patent issued under this application interpret the appended claims, the applicants wish to note that they do not intend any appended claim or claim element to reference 35 U.S.SC §112(f) unless the words “means” or “step” are expressly used in a particular claim.

Claims

1. A single integrated circuit, comprising: A signal path configured to generate an output signal from an input signal, wherein the signal path includes an amplifier configured to drive the output signal; A DC-DC power converter having a power inductor integrated in a single integrated circuit and configured to generate a power supply voltage from a source voltage to the amplifier; and A control circuit is provided for controlling the operation of the converter switch of the DC-DC power converter so that the power supply voltage tracks at least one of the input signal and the output signal.

2. The single integrated circuit according to claim 1, wherein, The control circuit is configured to control the operation of the converter switch only in the discontinuous current mode of the DC-DC power converter.

3. The single integrated circuit according to claim 1, wherein: The DC-DC power converter includes a bypass switch configured to bypass the operation of the converter switch; and The control circuit is configured to control the bypass switch to bypass the source voltage to the power supply voltage.

4. The single integrated circuit according to claim 3, wherein, The control circuit is configured to cause the bypass switch to bypass the source voltage to the power supply voltage when one of the input signal and the output signal is higher than a threshold amplitude.

5. The single integrated circuit according to claim 3, wherein, The control circuit is configured to cause the bypass switch to bypass the source voltage to the power supply voltage when the bandwidth of the DC-DC power converter is insufficient to allow the power supply voltage to track at least one of the input signal and the output signal.

6. The single integrated circuit according to claim 1, wherein, The control circuit is configured to control at least one of the duty cycle and switching frequency of the DC-DC power converter based on at least one of the input signal and the output signal.

7. The single integrated circuit according to claim 1, wherein, The control circuit is configured as follows: The duty cycle of the DC-DC power converter is controlled based on the input signal; and The switching frequency of the DC-DC power converter is controlled based on the output signal.

8. The single integrated circuit of claim 1, wherein the control circuit is configured to: The duty cycle of the DC-DC power converter is controlled based on at least one of the input signal and the output signal until the duty cycle reaches its limit; and When the duty cycle is at the duty cycle limit, the switching frequency of the DC-DC power converter is controlled based on at least one of the input signal and the output signal.

9. A method comprising, in a single integrated circuit: The output signal is generated from the input signal in the signal path, where, The signal path includes an amplifier configured to drive the output signal; A source voltage to DC-DC power converter generates a power supply voltage to the amplifier, wherein the DC-DC power converter has a power inductor integrated in the single integrated circuit; and The operation of the converter switch of the DC-DC power converter is controlled by a control circuit so that the power supply voltage tracks at least one of the input signal and the output signal.

10. The method of claim 9, further comprising controlling the switching of the converter only in the discontinuous current mode of the DC-DC power converter.

11. The method according to claim 9, wherein: The DC-DC power converter includes a bypass switch configured to bypass the operation of the converter switch; and The method further includes controlling the bypass switch to bypass the source voltage to the power supply voltage.

12. The method of claim 11, further comprising causing the bypass switch to bypass the source voltage to the power supply voltage when one of the input signal and the output signal is above a threshold amplitude.

13. The method of claim 11, further comprising, when the bandwidth of the DC-DC power converter is insufficient to allow the power supply voltage to track at least one of the input signal and the output signal, causing the bypass switch to bypass the source voltage to the power supply voltage.

14. The method of claim 9, further comprising controlling at least one of the duty cycle and switching frequency of the DC-DC power converter based on at least one of the input signal and the output signal.

15. The method of claim 9, further comprising: The duty cycle of the DC-DC power converter is controlled based on the input signal; and The switching frequency of the DC-DC power converter is controlled based on the output signal.

16. The method of claim 9, further comprising: The duty cycle of the DC-DC power converter is controlled based on at least one of the input signal and the output signal until the duty cycle reaches the duty cycle limit. and When the duty cycle is at the duty cycle limit, the switching frequency of the DC-DC power converter is controlled based on at least one of the input signal and the output signal.

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