Hybrid class-h / predictive class-g switching amplifier architecture

Abstract

A hybrid class-H / predictive class-G switching amplifier architecture and techniques for amplifying a signal (e.g., an audio signal) using such an architecture. One example method of amplifying generally includes delaying an input signal to generate a delayed version of the input signal, amplifying the delayed version of the input signal with an amplifier powered by a boost converter, and selectively controlling the boost converter to operate in at least one of a predictive class-G mode or a class-H mode based on an amplitude of the input signal.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit and priority of U.S. Patent Application No. 17 / 649,967, filed on February 4, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Certain aspects of this disclosure relate generally to electronic circuits, and more specifically to power amplifiers, such as audio amplifiers. Background Technology

[0004] A loudspeaker is a transducer that generates pressure waves in response to an input electrical signal, thus producing sound. The loudspeaker input signal can be generated by an audio amplifier (also called a "power amplifier"), which receives a relatively low-voltage analog audio signal and generates an amplified signal (with a relatively high voltage) to drive the loudspeaker. A dynamic loudspeaker typically consists of a lightweight diaphragm (cone) connected to a rigid basket (frame) via a flexible suspension (often called a spider) that constrains a voice coil to move axially through a cylindrical magnetic gap. When an input electrical signal is applied to the voice coil, the current in the coil generates a magnetic field, thus forming a linear motor. By changing the electrical signal from the audio amplifier, the mechanical force generated by the interaction between the magnet and the voice coil is modulated, causing the cone to move back and forth, thereby producing pressure waves that are interpreted as sound. Summary of the Invention

[0005] The systems, methods, and apparatus of this disclosure each have several aspects, none of which is solely responsible for their desired characteristics. Without limiting the scope of this disclosure as set forth in the appended claims, some features will now be briefly discussed. Upon consideration of this discussion, and especially after reading the section entitled "Detailed Description," it will be understood how the features of this disclosure provide the advantages described herein.

[0006] Certain aspects of this disclosure relate in general to a hybrid Class H / predictive Class G switched amplifier architecture and techniques for amplifying signals using such an architecture.

[0007] Some aspects of this disclosure relate to an amplifier circuit. The amplifier circuit typically includes: a delay element; an amplifier having an input coupled to the output of the delay element; a boost converter having an output coupled to a power supply input of the amplifier; and control logic having a first input coupled to the input of the delay element, a second input coupled to the output of the delay element, and an output having a control input coupled to the boost converter, wherein the control logic is configured to selectively control the boost converter to operate in at least one of a predictive Class G mode or a Class H mode based on the amplitude of an input signal.

[0008] Some aspects of this disclosure relate to a method of amplification. The method typically includes: delaying an input signal to generate a delayed version of the input signal; amplifying the delayed version of the input signal using an amplifier powered by a boost converter; and selectively controlling the boost converter to operate in at least one of a predictive Class G mode or a Class H mode based on the amplitude of the input signal.

[0009] Some aspects of this disclosure relate to an apparatus for amplification. The apparatus typically includes: means for delaying an input signal to generate a delayed version of the input signal; means for amplifying the delayed version of the input signal; means for adjusting power to the amplifier; and means for selectively controlling the power adjustment means to operate in at least one of a predictive Class G mode or Class H mode based on the amplitude of the input signal.

[0010] To achieve the foregoing and related objectives, one or more aspects include the features fully described below and specifically pointed out in the claims. The following description and drawings illustrate certain exemplary features of these one or more aspects in detail. However, these features indicate only a few of the various ways in which the principles of these aspects may be employed. Attached Figure Description

[0011] To gain a more detailed understanding of the foregoing features of this disclosure, a more specific description, which has been briefly summarized above, can be obtained by referring to various aspects, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings illustrate only certain typical aspects of this disclosure and are therefore not intended to limit its scope, as the specification may acknowledge other equally valid aspects.

[0012] Figure 1 Example audio amplifier systems in which various aspects of this disclosure can be practiced are illustrated.

[0013] Figure 2A The circuit diagram and corresponding signal timing diagram are of an example boost converter operating in bypass mode according to certain aspects of this disclosure.

[0014] Figure 2B It operates in boost mode according to certain aspects of this disclosure. Figure 2A The circuit diagram of the boost converter and the corresponding signal timing diagram.

[0015] Figure 2C This is a diagram illustrating the comparison of various voltage signals with the amplitude of an input signal according to certain aspects of this disclosure, illustrating bypass mode, Class H boost mode and predictive Class G boost mode.

[0016] Figure 3A This is a graph of the boost converter output signal and the corresponding current curve for tracking an example audio signal in a Class H amplifier.

[0017] Figure 3B It is a graph of the output signal of a boost converter for tracking the same audio signal in a hybrid Class H / predictive Class G amplifier with a single Class G threshold, and a corresponding current graph, according to certain aspects of this disclosure.

[0018] Figure 3C The output signal of the boost converter and the corresponding current curve are plots of the same audio signal in a hybrid Class H / predictive Class G amplifier having multiple Class G thresholds, according to certain aspects of this disclosure.

[0019] Figure 4 This is a block diagram of an example amplifier circuit for implementing a hybrid Class H / predictive Class G amplifier according to certain aspects of this disclosure.

[0020] Figure 5 This is a flowchart illustrating an example operation for amplifying an input signal according to certain aspects of this disclosure.

[0021] For ease of understanding, the same reference numerals have been used where possible to denote common elements in the accompanying drawings. It is conceivable that elements disclosed in one aspect may be usefully applied to other aspects without specific description. Detailed Implementation

[0022] Certain aspects of this disclosure provide a hybrid Class H / predictive Class G switching amplifier architecture and techniques for amplifying signals using such an architecture. This hybrid amplifier architecture can deliver very high power (e.g., >7W) at mid-to-high frequencies without compromising efficiency at low power (e.g., <1W).

[0023] The various aspects of the disclosure are described more fully below with reference to the accompanying drawings. However, this disclosure may be embodied in many different forms and should not be construed as limited to any particular structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey to those skilled in the art the scope of protection of this disclosure. Based on the teachings herein, those skilled in the art will understand that the scope of this disclosure is intended to cover any aspect of the disclosure herein, whether implemented independently or in combination with any other aspect of this disclosure. For example, any number of aspects set forth herein may be used to implement an apparatus or method of practice. Furthermore, the scope of this disclosure is intended to cover such apparatus or methods implemented using structures, functions, or structures and functions other than or different from the aspects of the disclosure set forth herein. It should be understood that any aspect of this disclosure herein may be embodied by one or more elements of the claims.

[0024] As used herein, the term "connected to" in various tenses of the verb "connect" can mean that element A is directly connected to element B or that other elements can be connected between element A and element B (i.e., element A is indirectly connected to element B). In the context of electronic components, the term "connected to" can also be used herein to mean that a conductor, trace, or other conductive material is used to electrically connect element A and element B (and any components electrically connected between them).

[0025] Example audio system with power amplifier

[0026] Figure 1 An example audio system 100 in which various aspects of this disclosure can be practiced is illustrated. However, it should be understood that various aspects of this disclosure can also be practiced in any of a variety of other suitable amplification scenarios.

[0027] like Figure 1 As shown, a digital signal processor (DSP) 102 can receive and process an audio signal 114 (e.g., a digital audio signal) by, for example, applying a digital filter designed to enhance audio quality. A digital-to-analog converter (DAC) 108 can be used to convert the filtered or otherwise processed digital signal 118 (or a further processed version thereof) generated by the DSP 102 into an analog signal 120. In some respects, the DAC can be implemented as part of the DSP 102 or amplifier 110. In some respects, amplifier 110 can be used to amplify the analog signal 120 to generate an amplified signal 122. The amplified signal 122 can drive a loudspeaker 112 to produce an acoustic output 124 (e.g., sound waves). In other words, amplifier 110 can be used as a loudspeaker driver.

[0028] High output volume in mobile devices is becoming increasingly important in next-generation devices. Higher volume translates to higher audio amplifier output power. Achieving high output power using the relatively low voltage provided by lithium-ion batteries can be challenging. Therefore, boost converters can be used to boost the battery voltage to a higher level to power audio power amplifiers (e.g., amplifier 110). In some respects, amplifier 110 can be implemented as a Class D amplifier due to the relatively high power efficiency associated with Class D amplifiers. For example, the efficiency of a Class D amplifier can be further improved by implementing it in an H-bridge configuration. However, some Class D amplifiers may not be able to deliver high power (e.g., above 4W) due to limited battery current and / or limited battery voltage. Therefore, in some respects, other amplifier architectures can be utilized to deliver high power.

[0029] Other amplifier types capable of delivering high power include Class H and Class G amplifiers, where the power rails are altered to follow the input speaker signal (a technique known as "rail voltage modulation"), where the input speaker signal can be an amplified signal. In Class H amplifiers, the power rails are continuously variable, while in Class G amplifiers, there may be different discrete levels at which the power rails switch, depending on the input speaker signal. Class H amplifiers are sometimes referred to as "rail trackers" because the amplifier modulates the power rails so that the rails are only a few volts larger than the amplifier's output signal, thus "tracking" the signal at any given time. Class G amplifiers, on the other hand, can have several power rails at different voltage levels and can switch between these rails as the output signal approaches each level.

[0030] Example of a hybrid Class H / predictive Class G amplifier

[0031] Ideally, a voltage regulator should provide a constant direct current (DC) output voltage regardless of changes in load current or input voltage. Voltage regulators can be categorized as linear regulators or switching regulators. While linear regulators are small and compact, many applications benefit from the increased efficiency of switching regulators. For example, a linear regulator can be implemented using a low dropout (LDO) regulator. Switching regulators can be implemented using switch-mode power supplies (SMPS) such as buck converters, boost converters, buck-boost converters, or charge pumps.

[0032] For example, a boost converter is a type of SMPS used to gradually increase the voltage (and gradually decrease the current) from the input to the output. A boost converter typically includes: (1) an inductor coupled between the input power supply node and the switching node; (2) a switch coupled between the switching node and a reference potential node; and (3) another switch (or diode) coupled between the switching node and a load (e.g., represented by a shunt capacitor element). The switch is typically implemented using a power transistor.

[0033] Figure 2A This is a circuit diagram of an example boost converter 200 operating in bypass mode according to certain aspects of this disclosure, and a corresponding signal timing diagram 210. The boost converter 200 includes an inductor element L1 and a switch (implemented by transistor M1), both coupled to a switching node (labeled "SW"). The boost converter 200 also includes a switch (implemented by transistor M0) coupled between the switching node and the output node of the boost converter, having an output supply voltage Vsup. These switches may each be implemented by one or more transistors, which may be n-type field-effect transistors (NFETs) or p-type field-effect transistors (PFETs). For example, although transistors M0 and M1 are... Figure 2A The output node is depicted as being implemented by an NFET, but the reader should understand that, in other respects, transistors M0 and M1 can be implemented as PFETs, in which case the gate drive polarity can be reversed. The output node can be coupled to an energy storage device (e.g., a capacitor element C1) and a load (e.g., an amplifier, such as amplifier 110).

[0034] The boost converter 200 can be configured to operate when the amplitude of the input signal (e.g., the amplitude of the amplifier input signal (such as analog signal 120)) is below a threshold (e.g., Figure 2C When the threshold is 252, it operates in bypass mode, such as Figure 2A As shown. When operating in bypass mode, the switch corresponding to transistor M1 can be turned off, while the switch corresponding to transistor M0 is turned on, thereby transferring energy stored in inductor L1 (if present) and supplying energy from input voltage source 202 (e.g., a battery with battery voltage Vbat) to capacitor C1 via transistor M0. As shown in timing diagram 210, when boost converter 200 is enabled (when the enable (EN) signal is logic 1), the gate drive signal for transistor M0 (labeled "M0_DRV") can be switched to and remain "high" (e.g., logic 1), while the gate drive signal for transistor M1 (labeled "M1_DRV") can remain "low" (e.g., logic 0), such that transistor M0 remains "on" and transistor M1 remains "off" during bypass mode.

[0035] The boost converter 200 can optionally operate in boost mode. In boost mode, transistors M0 and M1 can be controlled by a pulse width modulation (PWM) signal to turn these transistors on and off, thereby attempting to regulate the voltage across capacitor element C1 (i.e., voltage Vsup_output), where the output voltage is greater than the input voltage (Vbat).

[0036] Figure 2B It operates in boost mode according to certain aspects of this disclosure. Figure 2A The circuit diagram of the boost converter 200 and the corresponding signal timing diagram 220 are shown. The boost converter 200 can be configured to operate when the input signal amplitude is higher than a threshold (e.g., Figure 2C When the threshold value is 252, it operates in boost mode.

[0037] As shown in timing diagram 220, when operating in boost mode, gate drive signals M0_DRV and M1_DRV can alternate between "low" (e.g., logic 0) and "high" (e.g., logic 1), causing transistors M0 and M1 to modulate between complementary "on" and "off" states. In some respects, transistor M0 can be replaced by a diode, and when transistor M1 is in the "off" state, the energy stored in inductor L1 can be transferred to capacitor C1 via the diode, thus forward biasing the diode.

[0038] In boost mode, the boost converter 200 can provide power to the power input of the amplifier in a Class H amplifier architecture, allowing the supply voltage (i.e., the output voltage Vsup) to be regulated (using PWM applied to the gates of transistors M0 and M1) to track the amplifier output voltage above a threshold 252. Figure 2C (marked as "Vamp output") and provides sufficient amplifier headroom, such as Figure 2C As shown. While Class H amplifiers can efficiently deliver medium to high power levels (e.g., from 1W to 7W), some Class H amplifiers cannot support higher power (e.g., greater than 7W) due to limited battery current. On the other hand, Class G amplifiers can deliver higher power (e.g., greater than 7W) at mid-to-high frequencies, but may have relatively poorer efficiency compared to Class H amplifiers. Therefore, certain aspects of this disclosure provide an amplifier circuit configured to selectively control a boost converter to operate in either Class H mode or predictive Class G mode based on the amplitude of the input signal.

[0039] Figure 2CFigure 250 illustrates various voltage signals compared to the amplitude of an input signal according to certain aspects of this disclosure, illustrating bypass mode, Class H boost mode, and predictive Class G boost mode. As shown, the boost converter can be configured to, when the amplitude of the input signal (e.g., an analog amplifier input signal or a digital input signal) is below a first threshold 252, [as per relevant information]. Figure 2A The bypass mode described above operates. In bypass mode, the boost converter's output voltage Vsup can be compared with that of a voltage source (e.g., Figure 2A and Figure 2B The input voltage Vbat supplied by the input voltage source 202 (such as a battery) is the same as or at least substantially similar to that supplied by the input voltage source 202. The amplifier output signal Vamp increases linearly with the amplitude of the input signal (in both bypass mode and boost mode).

[0040] When the input signal amplitude exceeds the first threshold 252 but remains below the second threshold 254, the boost converter can be configured to (as per relevant information) Figure 2B The operation is described in Class H boost mode. As shown in the figure, when operating in Class H boost mode, the output voltage Vsup of the boost converter can increase (e.g., linearly) as the input signal amplitude increases between a first threshold 252 and a second threshold 254 to track the output voltage Vamp. In some examples, the headroom between the output voltage Vsup and the output voltage Vamp when operating in Class H boost mode can be relatively small compared to the headroom achieved in other operating modes. For example, the headroom in Class H boost mode can be 1.5V.

[0041] When the input signal amplitude exceeds the second threshold of 254, the boost converter can be configured to operate in predictive Class G boost mode. For example... Figure 2C As shown, when operating in predictive Class G boost mode, the boost converter's output signal Vsup can increase by multiple discrete levels (e.g., a step function) as the voltage Vamp increases. Furthermore, compared to Class H boost mode, predictive Class G boost mode provides a relatively large headroom, and this headroom margin can become even larger as the voltage Vamp increases, as illustrated in the figure.

[0042] Figure 3A Graph 300 shows the output signal 306 of the boost converter tracking example audio signal 302 in a Class H amplifier, and graph 310 shows the corresponding current curve illustrating the boost of the output current I from the boost converter. A complementary signal 304 to the audio signal 302 is also shown. The audio signal 302 (and its complement) can represent amplified output signals, such as those from... Figure 1 The amplified signal 122 is output from amplifier 110.

[0043] As shown in the figure, when operating in Class H boost mode, the boost converter output signal 306 typically tracks the absolute value (also known as amplitude) of the audio signal 302 while maintaining a certain headroom for the amplifier powered by the boost converter and generating the audio signal. However, when the amplitude of the audio signal 302 exceeds a certain level 307, clipping of the boost converter output signal 306 may occur (as shown at point 308), and the boost converter output signal 306 may not be able to provide the power required by the audio signal 302. This signal clipping may occur because the boost converter output current I is limited by the maximum battery current I (e.g., the input voltage source 202), as illustrated in the current profile 310. In other words, while Class H amplifiers can operate well for medium to high power levels, they may be limited to very high power levels (e.g., above level 307) and may not be able to provide sufficient headroom for the amplifier at these levels.

[0044] Clipping associated with Class H amplifiers can be addressed by using Class G amplifiers, which can deliver very high power (e.g., >7W). However, Class G amplifiers are generally less efficient than Class H amplifiers, which is undesirable. Therefore, certain aspects of this disclosure provide techniques and apparatus for selectively controlling the operation of a boost converter in either Class H mode or predictive Class G mode based on the amplitude of the input signal.

[0045] Figure 3B The graph 330 and the corresponding current graph 340 are plots of the boost converter output signal 336 of the same audio signal 302 in a hybrid Class H / predictive Class G amplifier having a single Class G threshold 337, according to certain aspects of this disclosure.

[0046] When the audio signal 302 is effectively predicted (e.g., for a predefined lead interval) to be below the Class G threshold 337, the hybrid Class H / predictive Class G amplifier can operate in Class H boost mode, and therefore, the boost converter output signal 336 can be similar to Figure 3A The boost converter output signal 306 is used because the boost converter output signal 336 typically tracks the amplitude of the audio signal 302. However, when the amplitude of the audio signal 302 is effectively predicted to exceed the Class G threshold 337 (e.g., in the lead interval), the hybrid Class H / predictive Class G amplifier can be configured to operate in a predictive Class G boost mode. In this mode, the hybrid Class H / predictive Class G amplifier can increase the boost converter output signal 336 before the audio signal 302 reaches an amplitude exceeding the Class G threshold 337 and the capability of the Class H boost mode. Therefore, with Figure 3A The boost converter output signal 306 differs from the signal 306 in the predictive Class G boost mode when delivering higher power to the amplifier. Figure 3BThe boost converter output signal 336 is not clipped, even if the boost converter output current Iboost may reach the maximum battery current Imaximum, as shown in the current curve 340.

[0047] like Figure 3B As shown, before the amplitude of the audio signal 302 exceeds the Class G threshold 337, the hybrid Class H / predictive Class G amplifier increases the boost converter output signal 336 to the same single voltage level, which is higher than the predicted amplitude of the audio signal 302, to provide sufficient headroom between the boost converter output signal 336 (e.g., the power supply voltage for the amplifier) ​​and the actual audio signal 302 amplified by the amplifier at a given time t. Although the boost converter output signal 336 begins to decline after its initial rise (as the predicted amplitude of the audio signal 302 begins to decrease), the hybrid amplifier can be designed such that the boost converter output signal 336 remains at a voltage higher than the amplitude of the actual audio signal 302 at any given time (e.g., at point 338), despite the decline due to the initial headroom generated during the ramp-up of the boost converter output signal 336 and the relatively slow decay time of the signal. This decay time can be balanced with the frequency of the audio signal 302 and can vary with the capacitance of the capacitor element C1 and the load current (for a given input current limit).

[0048] Figure 3C The graph 360 and the corresponding current graph 370 are plots of the boost converter output signal 366 of the same audio signal 302 in a hybrid Class H / predictive Class G amplifier having multiple Class G thresholds 367, according to certain aspects of this disclosure.

[0049] The boost converter output signal 366 can be similar to Figure 3B The boost converter output signal 336, in addition to Figure 3C The boost converter output signal 366 can achieve different Class G expected output values ​​369 (i.e., different voltage levels) based on which Class G threshold in the Class G threshold 367 the predicted amplitude of the audio signal 302 exceeds. For example, if the predicted amplitude of the audio signal 302 is 10V (which exceeds the first Class G threshold), the corresponding Class G expected output value 369 can be 14V, and the boost converter output signal 366 can be boosted to 14V. As another example, if the predicted amplitude of the audio signal 302 is 11V (which exceeds a second Class G threshold higher than the first Class G threshold), the corresponding Class G expected output value 369 can be 16V, and the boost converter output signal 366 can be boosted to 16V to provide sufficient headroom.

[0050] In some respects, the hybrid Class H / predictive Class G amplifier can be configured to maintain the boost converter output signal 366 for a pre-configured period of time when the Class G expected output value 369 is reached, in order to reduce the possibility that the amplitude of the boost converter output signal 366 decreases prematurely.

[0051] Figure 4 This is a block diagram of an example amplifier circuit 400 for implementing a hybrid Class H / predictive Class G amplifier according to certain aspects of this disclosure. The amplifier circuit 400 typically includes a delay element 402, a control logic unit 404, a boost converter 406, and an amplifier 408.

[0052] The delay element 402 can be implemented by any of a variety of suitable components (such as one or more buffers, one or more inverters, or combinations thereof) used to add delay to a signal. The delay element 402 can be implemented as (e.g.) Figure 4 The delay element 402 may be a separate component (as depicted) or implemented as part of another digital component (e.g., control logic unit 404 or DSP 102). The delay element 402 may receive an input signal (e.g., a digital input signal, such as audio signal 114 or digital signal 118) at an input node (labeled "D input"). The delay element 402 may be configured to delay the input signal to generate a delayed version of the input signal at the output of the delay element. By delaying the input signal, the delay element 402 provides additional time to allow control logic unit 404 to effectively implement lookahead features (i.e., predictive Class G functions) and configure the operating mode of boost converter 406 based on that point in the input signal before amplifier 408 amplifies it (or, in this case, its delayed version).

[0053] The boost converter 406 can be similar to Figure 2A and Figure 2B The boost converter 200 may have an output coupled to the power input of amplifier 408. Amplifier 408 may have an input coupled to the output of delay element 402. In some respects, amplifier 408 may be similar to Figure 1 The amplifier 110 in the amplifier can be used as (or include) a speaker driver or another type of amplifier. In other aspects, the amplifier 408 may include additional components and implement additional functions, such as those provided by a DAC (e.g., Figure 1 The DAC 108 performs digital-to-analog conversion. The amplifier 408 can be configured to amplify a delayed version of the input signal for output at the output node (labeled "V output") of the amplifier circuit 400.

[0054] Control logic unit 404 may have a first input coupled to the input of input node D and the input of delay element 402, a second input coupled to the output of delay element 402, and an output coupled to the control input (labeled "boost_ref") of boost converter 406. Control logic unit 404 may typically include a Class H controller 410, a Class G controller 412, and a multiplexer 414. Class H controller 410 may have an input coupled to the second input of control logic unit 404. Class G controller 412 may have one input coupled to the first input of control logic unit 404 and another input coupled to the second input of control logic unit 404. In some respects, Class H controller 410 may have 8-bit outputs (serial or parallel), allowing 256 distinct output values ​​to be effectively tracked sequentially; in other respects, Class H controllers may have outputs with more or fewer than 8 bits. In some respects, a Class G controller may have 4-bit outputs (serial or parallel), allowing 16 different output levels; in other respects, a Class G controller may have outputs with more or fewer than 4 bits. Multiplexer 414 may have a first set of inputs coupled to one or more outputs of Class H controller 410, a second set of inputs coupled to one or more outputs of Class G controller 412, and an output that acts as an output of control logic unit 404 and is coupled to a control input of boost converter 406. In some respects, multiplexer 414 may have one or more control inputs coupled to a set of outputs of Class G controller 412, such as... Figure 4 As shown, this is used for control selection between the first set of inputs and the second set of inputs of the multiplexer.

[0055] Depending on certain aspects, control logic unit 404 may be configured to selectively control boost converter 406 to operate in at least one of predictive Class G mode or Class H mode based on the amplitude of the input signal. In some aspects, predictive Class G mode may be (e.g., as...) Figure 3C In other respects, predictive G-class patterns can be (e.g., such as...) Figure 3B (In the context of) single-level predictive G-class patterns.

[0056] Depending on certain aspects, the control logic unit 404 may be configured to respond when the amplitude of the input signal is greater than a first threshold (e.g., Figure 3B and Figure 3C The G-class thresholds are 337 and 367 or Figure 2CWhen the second threshold 254 is reached, the boost converter 406 is controlled to operate in predictive Class G mode, such that the amplifier 408 has sufficient headroom to amplify the delayed version of the input signal. According to some aspects, the control logic unit 404 may be configured to control the boost converter 406 operating in predictive Class G mode to deflect the output capacitor (e.g., ...) of the boost converter 406 before the amplifier 408 receives the peak amplitude of the delayed version of the input signal. Figure 2A and Figure 2B The capacitor element C1 in the input signal is charged to a voltage higher than the peak amplitude of the input signal.

[0057] In some respects, the control logic unit 404 (or the comparator in the boost converter) can be configured to respond when the amplitude of the input signal is below a second threshold (e.g., Figure 2C When the amplitude of the input signal is below the first threshold (252), the boost converter 406 is controlled to operate in bypass mode. In some aspects, the control logic unit 404 may be configured to control the boost converter 406 to operate in Class H mode when the amplitude of the input signal is below the first threshold. According to some aspects, the control logic unit 404 may be configured to control the boost converter 406 to operate in Class H mode when the amplitude of the input signal is below the first threshold and above the second threshold (e.g., in...). Figure 2C When the threshold (between 252 and 254) is in the range, the boost converter 406 is controlled to operate in Class H mode.

[0058] In some respects, control logic unit 404 may be configured to change the reference voltage (e.g., boost ref) of boost converter 406 for operation in predictive Class G mode (or Class H mode) based on the amplitude of the input signal.

[0059] Example operation for zooming in

[0060] Figure 5 This is a flowchart of an example operation 500 for amplifying an input signal according to certain aspects of this disclosure. Operation 500 can be performed by an amplifier circuit (such as...) Figure 4 The amplifier circuit 400 is used to execute this.

[0061] Operation 500 may begin at block 502, where circuitry (and more specifically, e.g., a delay element, such as delay element 402) delays an input signal to generate a delayed version of that input signal. For example, the input signal may be a digital signal. At block 504, circuitry (and more specifically, e.g., an amplifier, such as amplifier 408) amplifies the delayed version of the input signal. The amplifier may be powered by a boost converter (e.g., boost converter 406). At block 506, circuitry (and more specifically, in some cases, control logic, such as control logic 404) may selectively control the boost converter to operate in at least one of a predictive Class G mode or a Class H mode based on the amplitude of the input signal. In some aspects, the circuitry may selectively control the boost converter to operate in at least one of a predictive Class G mode, a Class H mode, or a bypass mode based on the amplitude of the input signal.

[0062] According to some aspects, selectively controlling the boost converter at block 506 may involve controlling the boost converter to operate in a predictive Class G mode when the amplitude of the input signal is greater than a first threshold (e.g., a Class G threshold, such as Class G threshold 337 or 367), such that the amplifier has sufficient headroom to amplify a delayed version of the input signal. In this case, controlling the boost converter to operate in predictive Class G mode may include charging the output capacitor (e.g., capacitor C1) of the boost converter to a voltage higher than the peak amplitude of the input signal before the amplifier receives the peak amplitude of the delayed version of the input signal. In some cases, controlling the boost converter to operate in predictive Class G mode may include changing the reference voltage (boost_ref) for the boost converter based on the amplitude of the input signal. For some aspects, selectively controlling the boost converter at block 506 further involves controlling the boost converter to operate in Class H mode when the amplitude of the input signal is less than a first threshold and greater than a second threshold (e.g., a Class H threshold, such as battery voltage Vbat). Furthermore, selectively controlling the boost converter at block 506 may also include controlling the boost converter to operate in bypass mode when the amplitude of the input signal is below a second threshold. In other aspects, selectively controlling the boost converter at block 506 involves controlling the boost converter to operate in Class H mode when the amplitude of the input signal is below a first threshold.

[0063] According to some aspects, a predictive G-class pattern is a multi-level predictive G-class pattern (e.g., having multiple G-class thresholds, such as G-class threshold 367).

[0064] Example

[0065] In addition to the aspects mentioned above, specific combinations of these aspects are also within the scope of this disclosure, some of which are detailed below:

[0066] Aspect 1: A method of amplification, comprising: delaying an input signal to generate a delayed version of the input signal; amplifying the delayed version of the input signal using an amplifier powered by a boost converter; and selectively controlling the boost converter to operate in at least one of a predictive Class G mode or a Class H mode based on the amplitude of the input signal.

[0067] Aspect 2: According to the method of aspect 1, wherein the selective control includes: when the amplitude of the input signal is greater than a first threshold, controlling the boost converter to operate in the predictive Class G mode such that the amplifier has sufficient headroom to amplify the delayed version of the input signal.

[0068] Aspect 3: The method according to aspect 1 or 2, wherein controlling the boost converter to operate in the predictive Class G mode comprises: charging the output capacitor of the boost converter to a voltage higher than the peak amplitude of the input signal before the amplifier receives the peak amplitude of the delayed version of the input signal.

[0069] Aspect 4: The method according to any one of the preceding aspects, wherein the selective control further comprises: controlling the boost converter to operate in the Class H mode when the amplitude of the input signal is lower than the first threshold and greater than the second threshold.

[0070] Aspect 5: According to the method of aspect 4, the selective control further includes controlling the boost converter to operate in bypass mode when the amplitude of the input signal is lower than the second threshold.

[0071] Aspect 6: The method according to aspect 2 or 3, wherein the selective control further includes: controlling the boost converter to operate in the Class H mode when the amplitude of the input signal is below the first threshold.

[0072] Aspect 7: The method according to any one of the preceding aspects, wherein controlling the boost converter to operate in the predictive Class G mode comprises: changing the reference voltage for the boost converter based on the amplitude of the input signal.

[0073] Aspect 8: The method according to any one of the preceding aspects, wherein the predictive G-class pattern includes a multi-level predictive G-class pattern.

[0074] Aspect 9: An amplifier circuit comprising: a delay element; an amplifier having an input coupled to an output of the delay element; a boost converter having an output coupled to a power supply input of the amplifier; and control logic having a first input coupled to the input of the delay element, a second input coupled to the output of the delay element, and an output having a control input coupled to the boost converter, wherein the control logic is configured to selectively control the boost converter to operate in at least one of a predictive Class G mode or a Class H mode based on the amplitude of an input signal.

[0075] Aspect 10: The amplifier circuit according to Aspect 9, wherein: the delay element is configured to delay the input signal to generate a delayed version of the input signal; the amplifier is configured to amplify the delayed version of the input signal; and the control logic unit is configured to control the boost converter to operate in the predictive Class G mode when the amplitude of the input signal is greater than a first threshold, such that the amplifier has sufficient headroom to amplify the delayed version of the input signal.

[0076] Aspect 11: The amplifier circuit according to aspect 9 or 10, wherein the control logic component is configured to control the boost converter operating in the predictive Class G mode to charge the output capacitor of the boost converter to a voltage higher than the peak amplitude of the input signal before the amplifier receives the peak amplitude of the delayed version of the input signal.

[0077] Aspect 12: An amplifier circuit according to any one of aspects 9 to 11, wherein the control logic component is configured to control the boost converter to operate in the Class H mode when the amplitude of the input signal is lower than the first threshold and greater than the second threshold.

[0078] Aspect 13: The amplifier circuit according to aspect 12, wherein the control logic component is configured to control the boost converter to operate in bypass mode when the amplitude of the input signal is lower than the second threshold.

[0079] Aspect 14: The amplifier circuit according to aspect 10 or 11, wherein the control logic component is configured to control the boost converter to operate in the Class H mode when the amplitude of the input signal is lower than the first threshold.

[0080] Aspect 15: An amplifier circuit according to any one of Aspects 9 to 14, wherein the control logic component is configured to change the reference voltage of the boost converter for operation in the predictive Class G mode based on the amplitude of the input signal.

[0081] Aspect 16: An amplifier circuit according to any one of Aspects 9 to 15, wherein the control logic component comprises: a Class H controller having an input coupled to the second input of the control logic component; a Class G controller having an input coupled to the first input of the control logic component; and a multiplexer having a first set of inputs coupled to one or more outputs of the Class H controller, a second set of inputs coupled to one or more outputs of the Class G controller, and an output having the control input coupled to the boost converter.

[0082] Aspect 17: The amplifier circuit according to aspect 16, wherein the multiplexer has one or more control inputs coupled to a set of outputs of the Class G controller.

[0083] Aspect 18: The amplifier circuit according to any one of Aspects 9 to 17, wherein the predictive Class G mode comprises a multi-level predictive Class G mode.

[0084] Aspect 19: An amplifier circuit according to any one of aspects 9 to 18, wherein the amplifier includes a speaker driver.

[0085] Aspect 20: An amplification apparatus comprising: means for delaying an input signal to generate a delayed version of the input signal; means for amplifying the delayed version of the input signal; means for adjusting power to the amplifier; and means for selectively controlling the means for adjusting power to operate in at least one of a predictive Class G mode or a Class H mode based on the amplitude of the input signal.

[0086] Additional Notes

[0087] Certain aspects of this disclosure provide a hybrid Class H / predictive Class G amplifier architecture. This hybrid amplifier architecture operates by charging the boost converter output capacitor to a higher voltage (Class G, which still follows the speaker signal but has lead capability) before the signal peak occurs. When the signal peak occurs, the speaker signal should still be clean, although the battery current is limited, because the boost capacitor will be able to provide the remaining charge. Although the boost output may drop, the amplified signal should still be clean as long as the drop is not large enough to encroach on the speaker driver headroom. Thus, the hybrid Class H / predictive Class G amplifier architecture can deliver much higher power for the mid-to-high frequencies, even with limited battery current. Furthermore, low-power efficiency is not compromised.

[0088] The various operations described above can be performed by any suitable component capable of performing the corresponding function. This component may include various hardware and / or software components and / or modules, including but not limited to circuits, application-specific integrated circuits (ASICs), or processors. Generally, where the operations illustrated in the figures exist, those operations may have corresponding components with similar numbers plus functional components.

[0089] For example, components used for delay may include delay elements, such as... Figure 4 The delay element 402 is illustrated in the diagram. Components for amplification may include amplifiers, such as... Figure 1 The amplifier 110 shown or Figure 4 The amplifier 408 is depicted in the figure. Components for regulating power may include a voltage regulator, such as the boost converter 200 shown in Figure 2 or... Figure 4 The boost converter 406 is depicted in the diagram. Components for selective control may include control logic units, such as... Figure 4 The control logic component 404 is depicted in the document.

[0090] As used herein, the term "determine" encompasses a wide variety of actions. For example, "determine" can include calculation, operation, processing, deduction, investigation, lookup (e.g., searching in a table, database, or other data structure), assertion, and so on. Furthermore, "determine" can include receiving (e.g., receiving information), accessing (e.g., accessing data in memory), and so on. Additionally, "determine" can include parsing, selecting, choosing, building, and so on.

[0091] As used in this article, the phrase “at least one of the items” refers to any combination of those items (including a single member). For example, “at least one of a, b, or c” is intended to cover: a, b, c, ab, ac, bc, and abc, as well as any combination with multiple identical elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbb, cc, and ccc, or any other ordering of a, b, and c).

[0092] The methods disclosed herein include one or more steps or actions for implementing the described methods. The steps and / or actions of the methods may be interchanged without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and / or use of a particular step and / or action may be modified without departing from the scope of the claims.

[0093] It should be understood that the claims are not limited to the precise configurations and components illustrated above. Various modifications, alterations, and variations may be made in the arrangement, operation, and details of the methods and apparatus described above without departing from the scope of the claims.

Claims

1. A method of amplification, comprising: delaying an input signal to generate a delayed version of the input signal; amplifying the delayed version of the input signal with an amplifier powered by a boost converter; and selectively controlling, via a control logic, the boost converter to operate in at least one of a predictive class-G mode or a class-H mode based on an amplitude of the input signal, wherein the boost converter is selectively controlled, via the control logic, further based on the delayed version of the input signal.

2. The method of claim 1, wherein said selectively controlling comprises: controlling the boost converter to operate in the predictive class-G mode when the amplitude of the input signal is greater than a first threshold, such that the amplifier has sufficient headroom to amplify the delayed version of the input signal.

3. The method of claim 2, wherein controlling the boost converter to operate in the predictive Class-G mode comprises: charging an output capacitor of the boost converter to a voltage higher than a peak amplitude of the input signal before the amplifier receives the peak amplitude of the delayed version of the input signal.

4. The method of claim 2, wherein the selectively controlling further comprises: controlling the boost converter to operate in the class-H mode when the amplitude of the input signal is lower than the first threshold and greater than a second threshold.

5. The method of claim 4, wherein the selectively controlling further comprises: controlling the boost converter to operate in a bypass mode when the amplitude of the input signal is lower than the second threshold.

6. The method of claim 2, wherein said selectively controlling further comprises: controlling the boost converter to operate in the class-H mode when the amplitude of the input signal is lower than the first threshold.

7. The method of claim 2, wherein controlling the boost converter to operate in the predictive Class-G mode comprises: varying a reference voltage for the boost converter based on the amplitude of the input signal.

8. The method of claim 1, wherein the predictive class-G mode comprises a multi-level predictive class-G mode.

9. An amplification circuit, comprising: a delay element; an amplifier having an input coupled to an output of the delay element; a boost converter having an output coupled to a power input of the amplifier; and a control logic having a first input coupled to an input of the delay element, a second input coupled to the output of the delay element, and an output coupled to a control input of the boost converter, wherein the control logic is configured to selectively control the boost converter to operate in at least one of a predictive class-G mode or a class-H mode based on an amplitude of an input signal.

10. The amplification circuit of claim 9, wherein: the delay element is configured to delay the input signal to generate a delayed version of the input signal; the amplifier is configured to amplify the delayed version of the input signal; and the control logic is configured to control the boost converter to operate in the predictive class-G mode when the amplitude of the input signal is greater than a first threshold, such that the amplifier has sufficient headroom to amplify the delayed version of the input signal.

11. The amplification circuit of claim 10, wherein the control logic component is configured to control the boost converter operating in the predictive class-G mode to charge an output capacitor of the boost converter to a voltage higher than a peak amplitude of the input signal before the amplifier receives a peak amplitude of the delayed version of the input signal.

12. The amplification circuit of claim 10, wherein the control logic component is configured to control the boost converter to operate in the class-H mode when the amplitude of the input signal is below the first threshold and greater than a second threshold.

13. The amplification circuit of claim 12, wherein the control logic component is configured to control the boost converter to operate in a bypass mode when the amplitude of the input signal is below the second threshold.

14. The amplification circuit of claim 10, wherein the control logic component is configured to control the boost converter to operate in the class-H mode when the amplitude of the input signal is below the first threshold.

15. The amplification circuit of claim 10, wherein the control logic component is configured to vary a reference voltage for the boost converter operating in the predictive class-G mode based on the amplitude of the input signal.

16. The amplification circuit of claim 9, wherein the control logic component comprises: a class-H controller having an input coupled to the second input of the control logic component; a class-G controller having an input coupled to the first input of the control logic component; and a multiplexer having a first set of inputs coupled to one or more outputs of the class-H controller, a second set of inputs coupled to one or more outputs of the class-G controller, and an output coupled to the control input of the boost converter.

17. The amplification circuit of claim 16, wherein the multiplexer has one or more control inputs coupled to a set of outputs of the class-G controller.

18. The amplification circuit of claim 9, wherein the predictive class-G mode comprises a multi-stage predictive class-G mode.

19. The amplification circuit of claim 9, wherein the amplifier comprises a speaker driver.

20. An apparatus for amplification, comprising: means for delaying an input signal to generate a delayed version of the input signal; means for amplifying the delayed version of the input signal; means for regulating power to the means for amplifying; and means for selectively controlling the means for regulating power to operate in at least one of a predictive class-G mode or a class-H mode based on an amplitude of the input signal, wherein the means for selectively controlling is configured to selectively control the means for regulating power further based on the delayed version of the input signal. ​

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