A 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 exemplary method of amplification 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 the magnitude of the input signal.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS)

[0001] This application claims the benefit of and priority to U.S. patent application Ser. No. 17 / 649,967, filed Feb. 4, 2022, the entire contents of which are incorporated by reference herein.

[0002]

[0002] Certain aspects of the present disclosure relate generally to electronic circuits, and more particularly, to power amplifiers, such as audio amplifiers. [Background technology]

[0003]

[0003] A speaker is a transducer that generates pressure waves in response to an input electrical signal, thus producing sound. The speaker input signal may be generated by an audio amplifier (also called a "power amplifier"), which receives a relatively low-voltage analog audio signal and produces an amplified (with a relatively high voltage) signal to drive the speaker. 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 the voice coil to move axially through a cylindrical magnetic gap. When an input electrical signal is applied to the voice coil, a magnetic field is generated by the current in the coil, thereby forming a linear electric motor. By varying the electrical signal from the audio amplifier, the mechanical force generated by the interaction between the magnet and the voice coil is modulated, moving the cone back and forth, thereby producing pressure waves that are interpreted as sound. Summary of the Invention

[0004]

[0004] The systems, methods, and devices of the present disclosure each have several aspects, none of which is solely responsible for its desirable attributes. Without limiting the scope of the present disclosure as expressed by the following claims, several features will now be briefly discussed. After considering this discussion, and especially after reading the section entitled "Form for carrying out the invention", it will be understood how the features of the present disclosure provide the advantages described herein.

[0005]

[0005] Certain aspects of the present disclosure generally relate to hybrid class H / predictive class G switching amplifier architectures and techniques for amplifying signals using such architectures.

[0006]

[0006] Some aspects of the present disclosure are directed to an amplifier circuit that generally includes 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 coupled to a control input of the boost converter, the control logic being configured to selectively control the boost converter to operate in at least one of a predicted class G mode or a class H mode based on a magnitude of an input signal.

[0007]

[0007] Some aspects of the present disclosure are directed to a method of amplification. The method 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 predicted class G mode or a class H mode based on a magnitude of the input signal.

[0008] Some aspects of the present disclosure are directed to an apparatus for amplification that generally 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 means for adjusting power to operate in at least one of a predicted class-G mode or a class-H mode based on a magnitude of the input signal.

[0009] To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of only a few of the various ways in which the principles of the various aspects may be employed. [Brief description of the drawings]

[0010]

[0010] In order that the above-mentioned features of the present disclosure may be understood in detail, a more particular description, briefly summarized above, may be obtained by referring to the embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings illustrate only some typical embodiments of the present disclosure, and therefore should not be considered as limiting its scope, since the present description may admit of other equally effective embodiments. [Figure 1]

[0011] 1 illustrates an exemplary audio amplifier system in which aspects of the present disclosure may be practiced. [Figure 2A]

[0012] 1 is a circuit diagram and corresponding signal timing diagram of an example boost converter operating in bypass mode in accordance with some aspects of the present disclosure. [Figure 2B]

[0013] 2B is a circuit diagram and corresponding signal timing diagram of the boost converter of FIG. 2A operating in boost mode according to some embodiments of the present disclosure. [Figure 2C]

[0014] 1 is a graph of various voltage signals compared to the magnitude of an input signal illustrating a bypass mode, a Class H boost mode, and a predicted Class G boost mode, in accordance with some aspects of the present disclosure. [Figure 3A]

[0015] 1 is a plot of a boost converter output signal tracking an example audio signal in a class H amplifier and corresponding current plot. [Figure 3B]

[0016] 1 is a plot of a boost converter output signal tracking the same audio signal in a hybrid Class H / Predictive Class G amplifier with a single Class G threshold, and corresponding current plot, in accordance with some aspects of the present disclosure. [Figure 3C]

[0017] 1 is a plot of a boost converter output signal tracking the same audio signal in a hybrid Class H / Predictive Class G amplifier with multiple Class G thresholds, and corresponding current plots, according to some aspects of the disclosure. [Figure 4]

[0018] FIG. 2 is a block diagram of an example amplifier circuit implementing a hybrid Class H / Predictive Class G amplifier in accordance with some aspects of the present disclosure. [Diagram 5]

[0019] 4 is a flow diagram of an example operation for amplifying an input signal according to some aspects of the present disclosure.

[0011]

[0020] For ease of understanding, the same reference numbers have been used, where possible, to designate identical elements common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012]

[0021] Some aspects of the present disclosure provide hybrid Class H / Predictive Class G switching amplifier architectures and techniques for amplifying signals using such architectures. Such hybrid amplifier architectures can provide very high power (e.g., >7W) at mid-to-high frequencies without compromising efficiency at low power (e.g., <1W).

[0013]

[0022] Various aspects of the present disclosure will be described more fully below with reference to the accompanying drawings. However, the present disclosure may be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout the present disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein, those skilled in the art will understand that the scope of the present disclosure is intended to encompass all aspects of the present disclosure disclosed herein, regardless of whether they are implemented independently of or in combination with any other aspects of the present disclosure. For example, an apparatus can be implemented or a method can be practiced using any number of the aspects described herein. It is intended that the scope of the present disclosure encompass such an apparatus or method that is implemented using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the present disclosure described herein. It is understood that any aspect of the present disclosure disclosed herein can be embodied by one or more elements of a claim.

[0014]

[0023] As used herein, the term "connected with" in various tenses of the verb "connect" can mean that element A is directly connected to element B, or that other elements may be connected between element A and element B (i.e., element A is indirectly connected to element B). In the case of electrical components, the term "connected with" can also be used herein to mean electrically connecting element A and element B (and any components electrically connected between them) using a wire, trace, or other conductive material.

[0015] Exemplary Audio System Having a Power Amplifier

[0024] 1 illustrates an example audio system 100 in which aspects of the present disclosure may be practiced. However, it should be understood that aspects of the present disclosure may also be practiced in any of a variety of other suitable amplification scenarios.

[0016]

[0025] As shown in FIG. 1, a digital signal processor (DSP) 102 may receive and process an audio signal 114 (e.g., a digital audio signal), for example, by applying a digital filter intended to improve audio quality. The filtered or otherwise processed digital signal 118 (or a further processed version of that signal) generated by the DSP 102 may be converted to an analog signal 120 using a digital-to-analog converter (DAC) 108. In some aspects, the DAC may be implemented as part of the DSP 102 or the amplifier 110. In some aspects, the analog signal 120 may be amplified using the amplifier 110 to generate an amplified signal 122. The amplified signal 122 may drive a speaker 112 to generate an acoustic output 124 (e.g., sound waves). In other words, the amplifier 110 may function as a speaker driver.

[0017]

[0026] High output sound volume in mobile devices is becoming increasingly important in next generation devices. Higher sound volume translates to higher audio amplifier output power. With the relatively low voltage provided by lithium-ion batteries, it may be difficult to achieve higher output power. Therefore, a boost converter may be used to boost the battery voltage to a higher level to feed an audio power amplifier (e.g., amplifier 110). In some aspects, amplifier 110 may be implemented as a class D amplifier due to the relatively high power efficiency associated with class D amplifiers. The efficiency of class D amplifiers may be further improved, for example, by implementing class D amplifiers in an H-bridge configuration. However, some class D amplifiers may not be capable of delivering high power (e.g., greater than 4W) due to limited battery current and / or limited battery voltage. Therefore, in some aspects, other amplifier architectures may be utilized to deliver high power.

[0018]

[0027] Other amplifier types capable of delivering high power include class H and class G amplifiers, where the power rails are varied to follow the input speaker signal (referred to as "rail voltage modulation"), which may be the amplified signal 122. In a class H amplifier, the power rails are continuously variable, while in a class G amplifier there may be different discrete levels at which the power rails switch based on the input speaker signal. Class H amplifiers are sometimes called "rail trackers" because the amplifier modulates the power rails so that the rails are only a few volts greater than the amplifier output signal, and "track" this signal at any given time. A class G amplifier, on the other hand, may have several power rails at different voltage levels, and may switch between the rails as the output signal approaches each level.

[0019] An exemplary hybrid class H / predictive class G amplifier

[0028] A voltage regulator ideally provides a constant direct current (DC) output voltage regardless of changes in load current or input voltage. Voltage regulators may be classified as linear regulators or switching regulators. Linear regulators tend to be small and compact, but many applications can benefit from the increased efficiency of switching regulators. A linear regulator may be implemented, for example, by a low-dropout (LDO) regulator. A switching regulator may be implemented, for example, by a switched-mode power supply (SMPS), such as a buck converter, boost converter, buck-boost converter, or charge pump.

[0020]

[0029] For example, a boost converter is a type of SMPS for stepping up the voltage (and stepping down the current) from the input to the output. A boost converter typically includes (1) an inductor coupled between an input supply node and a 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 capacitive element). The switch is typically implemented using a power transistor.

[0021]

[0030] FIG. 2A is a circuit diagram and corresponding signal timing diagram 210 of an example boost converter 200 operating in bypass mode according to some aspects of the disclosure. The boost converter 200 includes an inductive 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 an output node of the boost converter having an output supply voltage Vsup_out. The switches may each be implemented by one or more transistors, which may be n-type field-effect transistors (NFET) or p-type field-effect transistors (PFET). For example, although transistors M0 and M1 are shown in FIG. 2A as being implemented by NFETs, the reader should understand that transistors M0 and M1 may be implemented as PFETs in other aspects, in which case the gate drive polarity may be reversed. The output node may be coupled to an energy storage device (eg, a capacitive element C1) and a load (eg, an amplifier such as amplifier 110).

[0022]

[0031] The boost converter 200 may be configured to operate in a bypass mode, as shown in Figure 2A, when the magnitude of the input signal (e.g., the magnitude of the amplifier input signal, such as the analog signal 120) falls below a threshold (e.g., threshold 252 in Figure 2C). While operating in the bypass mode, the switch corresponding to transistor M1 may be opened and the switch corresponding to transistor M0 is closed to transfer the energy stored in the inductive element L1 (if any) and provide energy from the input voltage source 202 (e.g., a battery having a battery voltage Vbat) through transistor M0 to the capacitive element C1. As shown in timing diagram 210, the gate drive signal for transistor M0 (labeled "M0_DRV") may transition to and remain in a "high" (e.g., logic 1) state while boost converter 200 is enabled (while the enable (EN) signal is logic 1), while the gate drive signal for transistor M1 (labeled "M1_DRV") may remain "low" (e.g., logic 0) such that transistor M0 remains in an "on" state and transistor M1 remains in an "off" state during bypass mode.

[0023]

[0032] Boost converter 200 may alternatively be operated in boost mode, in which transistors M0 and M1 may be controlled by a pulse-width modulation (PWM) signal to open and close the transistors to regulate the voltage across capacitive element C1 (i.e., the voltage Vsup_out), where the output voltage is greater than the input voltage (Vbat).

[0024]

[0033] 2B is a circuit diagram and corresponding signal timing diagram 220 of the boost converter 200 of FIG. 2A operating in boost mode according to some aspects of the disclosure. The boost converter 200 can be configured to operate in boost mode when the magnitude of the input signal is above a threshold (e.g., threshold 252 of FIG. 2C).

[0025]

[0034] As shown in timing diagram 220, while operating in boost mode, gate drive signals M0_DRV and M1_DRV may alternate between “low” (e.g., logic 0) and “high” (e.g., logic 1) such that transistors M0 and M1 are modulated between complementary “on” and “off” states. In some aspects, transistor M0 may be replaced with a diode, and energy stored in inductive element L1 may be transferred through the diode to capacitive element C1 when transistor M1 is in the “off” state such that the diode is forward biased.

[0026]

[0035] In boost mode, boost converter 200 may provide power to the power input of an amplifier in a class H amplifier architecture, such that the supply voltage (i.e., voltage Vsup_out) may be adjusted (using PWM applied to the gates of transistors M0 and M1) to track the amplifier output voltage (labeled "Vamp_out" in FIG. 2C) above a threshold 252 and provide sufficient amplifier headroom margin, as shown in FIG. 2C. Class H amplifiers may be capable of efficiently delivering medium to high power levels (e.g., 1W to 7W), but some class H amplifiers are not capable of supporting higher power (e.g., power above 7W) because they are battery current limited. On the other hand, class G amplifiers may be capable of delivering higher power (e.g., power greater than 7W) at medium to high frequencies, but may have relatively low efficiency compared to class H amplifiers. Accordingly, some aspects of the present disclosure provide an amplifier circuit configured to selectively control a boost converter to operate in a class H mode or a predicted class G mode based on the magnitude of the input signal.

[0027]

[0036] 2C is a graph 250 of various voltage signals compared to the magnitude of the input signal, illustrating a bypass mode, a class H boost mode, and a predicted class G boost mode, according to some aspects of the disclosure. As shown, the boost converter can be configured to operate in a bypass mode (as described with respect to FIG. 2A) when the magnitude of the input signal (e.g., an analog amplifier input signal or a digital input signal) falls below a first threshold 252. In the bypass mode, the output voltage Vsup_out of the boost converter can be the same as, or at least substantially similar to, the input voltage Vbat provided by a voltage source such as a battery (e.g., the input voltage source 202 in FIGS. 2A and 2B). The amplifier output signal Vamp_out increases linearly with the magnitude of the input signal (in both bypass and boost modes).

[0028]

[0037] The boost converter may be configured to operate in class H boost mode (as described with respect to FIG. 2B) when the magnitude of the input signal exceeds the first threshold 252 but remains below the second threshold 254. As shown, when operating in class H boost mode, the output voltage Vsup_out of the boost converter may increase (e.g., linearly) as the magnitude of the input signal increases between the first threshold 252 and the second threshold 254 to track the voltage Vamp_out. In some examples, when operating in class H boost mode, the headroom between the output voltages Vsup_out and Vamp_out may be relatively small compared to the headroom space achieved in other operating modes. For example, the headroom in class H boost mode may be 1.5V.

[0029]

[0038] The boost converter may be configured to operate in a predictive class G boost mode when the magnitude of the input signal exceeds a second threshold 254. As shown in FIG. 2C, when operating in the predictive class G boost mode, the output signal Vsup_out of the boost converter may increase with multiple discrete levels (e.g., a step function) as the voltage Vamp_out increases. Furthermore, the predictive class G boost mode may provide a relatively large headroom compared to the class H boost mode, and this headroom margin may be larger as the voltage Vamp_out increases, as shown.

[0030]

[0039] 3A is a plot 300 of a boost converter output signal 306 tracking an example audio signal 302 in a class H amplifier, and a corresponding current plot 310 showing the output current Iboost from the boost converter. Also shown is a complement 304 of the audio signal 302. The audio signal 302 (and its complement) may represent an amplified output signal, such as the amplified signal 122 from the output of the amplifier 110 in FIG.

[0031]

[0040] As shown, while operating in class H boost mode, the boost converter output signal 306 generally tracks the absolute value (also called magnitude) of the audio signal 302 while maintaining some headroom for the amplifier powered by the boost converter to generate the audio signal. However, when the magnitude of the audio signal 302 exceeds a certain level 307, clipping of the boost converter output signal 306 (as shown at point 308) may occur 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 due to the boost converter output current Iboost being limited by the maximum battery current Imax (e.g., of the input voltage source 202), as shown in current plot 310. In other words, while a class H amplifier may work well for medium to high power levels, the class H amplifier may be limited at very high power levels (e.g., above level 307) and may not be able to provide enough headroom for the amplifier at these levels.

[0032]

[0041] The clipping associated with class H amplifiers can be addressed by using class G amplifiers that can deliver very high power (e.g., >7W). However, class G amplifiers are typically less efficient than class H amplifiers, which is undesirable. Therefore, some aspects of the present disclosure provide techniques and apparatus to selectively control a boost converter to operate in a class H mode or a predicted class G mode based on the magnitude of the input signal.

[0033]

[0042] FIG. 3B is a plot 330 of a boost converter output signal 336 tracking the same audio signal 302 in a hybrid Class H / Predictive Class G amplifier with a single Class G threshold 337, and a corresponding current plot 340, in accordance with some aspects of the disclosure.

[0034]

[0043] When the audio signal 302 is effectively predicted (e.g., for a predefined look-ahead interval) to be below the class-G threshold 337, the hybrid class-H / predictive class-G amplifier may operate in class-H boost mode, and thus the boost converter output signal 336 may be similar to the boost converter output signal 306 in FIG. 3A in that the boost converter output signal 336 may generally track the magnitude of the audio signal 302. However, the hybrid class-H / predictive class-G amplifier may be configured to operate in predictive class-G boost mode when the magnitude of the audio signal 302 is effectively predicted (e.g., at the look-ahead interval) to be above the class-G threshold 337. In this mode, the hybrid class-H / predictive class-G amplifier may increase the boost converter output signal 336 before the audio signal 302 reaches a magnitude that exceeds the class-G threshold 337 and the capabilities of the class-H boost mode. As a result, unlike the boost converter output signal 306 of FIG. 3A, the boost converter output signal 336 of FIG. 3B operating in a predictive class G boost mode is not clipped when delivering higher power to the amplifier, even though the boost converter output current Iboost may reach the maximum battery current Imax, as shown in current plot 340.

[0035]

[0044] 3B, before the magnitude 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 higher than the predicted magnitude of the audio signal 302 to provide sufficient headroom between the boost converter output signal 336 (e.g., the supply voltage for the amplifier) ​​and the actual audio signal 302 being amplified by the amplifier at a given time t. Although the boost converter output signal 336 will begin to droop after initially rising (due to the predicted magnitude of the audio signal 302 beginning to decrease), the hybrid amplifier can be designed such that despite the droop, the boost converter output signal 336 will remain at a higher voltage than the magnitude of the actual audio signal 302 at any given time (e.g., point 338) due to the initial headroom created during the ramp-up of the boost converter output signal 336 and the relatively slow decay time of this signal. This decay time may be balanced with the frequency of the audio signal 302 and may be a function of the capacitance of the capacitive element C1 (for a given input current limit) and the load current.

[0036]

[0045] FIG. 3C is a plot 360 of a boost converter output signal 366 tracking the same audio signal 302 in a hybrid Class H / Predictive Class G amplifier with multiple Class G thresholds 367, and a corresponding current plot 370, in accordance with some aspects of the disclosure.

[0037]

[0046] The boost converter output signal 366 may be similar to the boost converter output signal 336 of FIG. 3B, however, the boost converter output signal 366 of FIG. 3C may achieve a different class G expected output value 369 (i.e., a different voltage level) based on which class G threshold 367 the predicted magnitude of the audio signal 302 exceeds. For example, if the predicted magnitude of the audio signal 302 is 10V (above a first class G threshold), the corresponding class G expected output value 369 may be 14V and the boost converter output signal 366 may be boosted to 14V. As another example, if the predicted magnitude of the audio signal 302 is 11V (above a second class G threshold that is higher than the first class G threshold), the corresponding class G expected output value 369 may be 16V and the boost converter output signal 366 may be boosted to 16V to provide sufficient headroom.

[0038]

[0047] In some aspects, the hybrid Class H / Predictive Class G amplifier may be configured to maintain the boost converter output signal 366 at the Class G predicted output value 369 for a preconfigured period of time to reduce the likelihood of a premature decrease in the magnitude of the boost converter output signal 366.

[0039]

[0048] 4 is a block diagram of an example amplifier circuit 400 implementing a hybrid class H / predictive class G amplifier in accordance with some aspects of the present disclosure. The amplifier circuit 400 may generally include a delay element 402, control logic 404, a boost converter 406, and an amplifier 408.

[0040]

[0049] The delay element 402 may be implemented by any of a variety of suitable components that add delay to a signal, such as one or more buffers, one or more inverters, or a combination thereof. The delay element 402 may be implemented as a separate component (as shown in FIG. 4) or as part of another digital component (e.g., the control logic 404 or the DSP 102). The delay element 402 may receive an input signal (e.g., a digital input signal such as the audio signal 114 or the digital signal 118) at an input node (labeled “Din”). 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 may provide additional time to allow the control logic 404 to effectively implement a look-ahead function (i.e., a predictive class-G function) and configure the operating mode of the boost converter 406 based on a point in the input signal before the amplifier 408 amplifies that point (or, in this case, a delayed version thereof).

[0041]

[0050] The boost converter 406 may be similar to the boost converter 200 of FIGS. 2A and 2B and may have an output coupled to a power input of the amplifier 408. The amplifier 408 may have an input coupled to an output of the delay element 402. In some aspects, the amplifier 408 may be similar to the amplifier 110 in FIG. 1 and may function 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 digital-to-analog conversion by a DAC (e.g., the DAC 108 of FIG. 1). The amplifier 408 may be configured to amplify a delayed version of the input signal to be output at an output node (labeled “Vout”) of the amplifier circuit 400.

[0042]

[0051] The control logic 404 may have a first input coupled to the input node Din and the input of the delay element 402, a second input coupled to the output of the delay element 402, and an output coupled to a control input (labeled "Boost_ref") of the boost converter 406. The control logic 404 may generally include a Class H controller 410, a Class G controller 412, and a multiplexer 414. The Class H controller 410 may have an input coupled to the second input of the control logic 404. The Class G controller 412 may have one input coupled to the first input of the control logic 404 and another input coupled to the second input of the control logic. In some aspects, the Class H controller 410 may have an 8-bit output (serial or parallel) allowing 256 different output values ​​to effectively implement continuous tracking, while in other aspects the Class H controller may have more or less than 8-bit output. In some aspects, the Class G controller may have a 4-bit output (serial or parallel) allowing for 16 different output levels, while in other aspects the Class G controller may have more or less than 4-bit outputs. A multiplexer 414 may have a first set of inputs coupled to one or more outputs of the Class H controller 410, a second set of inputs coupled to one or more outputs of the Class G controller 412, and an output that serves as an output of the control logic 404 and is coupled to a control input of the boost converter 406. In some aspects, the multiplexer 414 may have one or more control inputs coupled to a set of outputs of the Class G controller 412, as shown in FIG. 4, for controlling selection between the first and second sets of inputs to the multiplexer.

[0043]

[0052] According to some aspects, control logic 404 may be configured to selectively control boost converter 406 to operate in at least one of a predicted class-G mode or a class-H mode based on the magnitude of the input signal. In some aspects, the predicted class-G mode may be a multi-level predicted class-G mode (e.g., as in FIG. 3C), while in other aspects, the predicted class-G mode may be a single-level predicted class-G mode (e.g., as in FIG. 3B).

[0044]

[0053] According to some aspects, the control logic 404 may be configured to control the boost converter 406 to operate in a predictive class-G mode when the magnitude of the input signal is greater than a first threshold (e.g., the class-G thresholds 337 and 367 in FIGS. 3B and 3C, or the second threshold 254 in FIG. 2C) such that the amplifier 408 has sufficient headroom to amplify the delayed version of the input signal. According to some aspects, the control logic 404 may be configured to control the boost converter 406 operating in a predictive class-G mode to charge an output capacitor (e.g., the capacitive element C1 in FIGS. 2A and 2B) of the boost converter 406 to a voltage higher than the peak value of the input signal before the peak value of the delayed version of the input signal is received by the amplifier 408.

[0045]

[0054] In some aspects, the control logic 404 (or a comparator in the boost converter) may be configured to control the boost converter 406 to operate in a bypass mode when the magnitude of the input signal is less than a second threshold (e.g., the first threshold 252 in FIG. 2C). In some aspects, the control logic 404 may be configured to control the boost converter 406 to operate in a class H mode when the magnitude of the input signal is less than the first threshold. According to some aspects, the control logic 404 may be configured to control the boost converter 406 to operate in a class H mode when the magnitude of the input signal is less than the first threshold and greater than a second threshold (e.g., between the thresholds 252 and 254 in FIG. 2C).

[0046]

[0055] In some aspects, the control logic 404 may be configured to modify a reference voltage (e.g., Boost_ref) for the boost converter 406 operating in a predicted class G mode (or class H mode) based on the magnitude of the input signal.

[0047] Exemplary Operations for Amplification

[0056] 5 is a flow diagram of an example operation 500 for amplifying an input signal according to some aspects of the disclosure. The operation 500 may be performed by an amplifier circuit such as the amplifier circuit 400 of FIG.

[0048]

[0057] The operations 500 may begin at block 502, where a circuit (more specifically, a delay element, such as delay element 402, for example) may delay an input signal to generate a delayed version of the input signal. The input signal may be, for example, a digital signal. At block 504, a circuit (more specifically, an amplifier, such as amplifier 408, for example) may amplify the delayed version of the input signal. The amplifier may be powered by a boost converter (e.g., boost converter 406). At block 506, a circuit (more specifically, in some cases, control logic, such as control logic 404, for example) may selectively control the boost converter to operate in at least one of a predicted class G mode or a class H mode based on the magnitude of the input signal. In some aspects, the circuit may selectively control the boost converter to operate in at least one of a predicted class G mode, a class H mode, or a bypass mode based on the magnitude of the input signal.

[0049]

[0058] According to some aspects, selectively controlling the boost converter in block 506 may involve controlling the boost converter to operate in a predictive class-G mode when the magnitude of the input signal is greater than a first threshold (e.g., a class-G threshold, such as a class-G threshold of 337 or 367) such that the amplifier has sufficient headroom to amplify the delayed version of the input signal. In this case, controlling the boost converter to operate in the predictive class-G mode may include charging an output capacitor (e.g., capacitor C1) of the boost converter to a voltage higher than the peak value of the input signal before the peak value of the delayed version of the input signal is received by the amplifier. In some cases, controlling the boost converter to operate in the predictive class-G mode may include modifying a reference voltage (Boost_ref) for the boost converter based on the magnitude of the input signal. In some aspects, selectively controlling the boost converter in block 506 further includes controlling the boost converter to operate in a class-H mode when the magnitude of the input signal is less than the first threshold and greater than a second threshold (e.g., a class-H threshold, such as a battery voltage Vbat). Additionally, selectively controlling the boost converter in block 506 may further include controlling the boost converter to operate in a bypass mode when the magnitude of the input signal is less than a second threshold. In another aspect, selectively controlling the boost converter in block 506 includes controlling the boost converter to operate in a class H mode when the magnitude of the input signal is less than a first threshold.

[0050]

[0059] According to some aspects, the predicted Class G mode is a multi-level predicted Class G mode (eg, having multiple Class G thresholds, such as Class G threshold 367).

[0051] Exemplary Aspects

[0060] In addition to the various aspects described above, specific combinations of aspects are within the scope of the present disclosure, some of which are detailed below.

[0052]

[0061] Aspect 1: A method including 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 predicted class G mode or a class H mode based on a magnitude of the input signal.

[0053]

[0062] Aspect 2: The method of aspect 1, wherein selectively controlling includes controlling the boost converter to operate in a predictive Class G mode when the magnitude of the input signal is greater than a first threshold so that the amplifier has sufficient headroom to amplify a delayed version of the input signal.

[0054]

[0063] Aspect 3: The method of aspect 1 or 2, wherein controlling the boost converter to operate in a predictive Class G mode includes charging an output capacitor of the boost converter to a voltage higher than the peak value of the input signal before the peak value of the delayed version of the input signal is received by the amplifier.

[0055]

[0064] Aspect 4: A method as described in any of aspects 1 to 3, wherein selectively controlling further includes controlling the boost converter to operate in Class H mode when the magnitude of the input signal is less than a first threshold and greater than a second threshold.

[0056]

[0065] Aspect 5: The method of aspect 4, wherein selectively controlling further comprises controlling the boost converter to operate in the bypass mode when the magnitude of the input signal is less than a second threshold.

[0057]

[0066] Aspect 6: The method of aspect 2 or 3, wherein selectively controlling further comprises controlling the boost converter to operate in Class H mode when the magnitude of the input signal is less than a first threshold.

[0058]

[0067] Aspect 7: A method as described in any of aspects 1 to 6, wherein controlling the boost converter to operate in the predictive class G mode includes modifying a reference voltage for the boost converter based on the magnitude of the input signal.

[0059]

[0068] Example 8: The method of any of Examples 1 to 7, wherein the predicted class G mode includes a multi-level predicted class G mode.

[0060]

[0069] Aspect 9: An amplifier circuit comprising: 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 coupled to a control input of the boost converter, the control logic being configured to selectively control the boost converter to operate in at least one of a predicted class G mode or a class H mode based on a magnitude of the input signal.

[0061]

[0070] Aspect 10: An amplifier circuit as described in aspect 9, wherein the delay element is configured to delay an 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 a predicted class G mode when the magnitude of the input signal is greater than a first threshold so that the amplifier has sufficient headroom to amplify the delayed version of the input signal.

[0062]

[0071] Aspect 11: An amplifier circuit as described in aspect 9 or 10, wherein the control logic is configured to control a boost converter operating in a predictive Class G mode to charge an output capacitor of the boost converter to a voltage higher than the peak value of the input signal before the peak value of the delayed version of the input signal is received by the amplifier.

[0063]

[0072] Aspect 12: An amplifier circuit described in any one of aspects 9 to 11, wherein the control logic is configured to control the boost converter to operate in Class H mode when the magnitude of the input signal is smaller than a first threshold and greater than a second threshold.

[0064]

[0073] Aspect 13: The amplifier circuit of aspect 12, wherein the control logic is configured to control the boost converter to operate in the bypass mode when the magnitude of the input signal is less than a second threshold.

[0065]

[0074] Aspect 14: The amplifier circuit of aspect 10 or 11, wherein the control logic is configured to control the boost converter to operate in Class H mode when the magnitude of the input signal is less than a first threshold.

[0066]

[0075] Aspect 15: An amplifier circuit as described in any one of aspects 9 to 14, wherein the control logic is configured to modify a reference voltage for a boost converter operating in a predictive class G mode based on the magnitude of the input signal.

[0067]

[0076] Aspect 16: An amplifier circuit as described in any of aspects 9 to 15, wherein the control logic includes: a class H controller having an input coupled to a second input of the control logic; a class G controller having an input coupled to a first input of the control logic; 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 a control input of the boost converter.

[0068]

[0077] Example 17: The amplifier circuit of example 16, wherein the multiplexer has one or more control inputs coupled to the set of outputs of the Class G controller.

[0069]

[0078] Aspect 18: The amplifier circuit according to any one of aspects 9 to 17, wherein the predicted class G mode includes a multilevel predicted class G mode.

[0070]

[0079] Aspect 19: The amplifier circuit of any one of aspects 9 to 18, wherein the amplifier includes a speaker driver.

[0071]

[0080] Aspect 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 adjusting power to the amplifier; and means for selectively controlling the means for adjusting power to operate in at least one of a predicted class G mode or a class H mode based on a magnitude of the input signal.

[0072] Additional Considerations

[0081] Some aspects of the present disclosure provide a hybrid class H / predictive class G amplifier architecture. The 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 look-ahead capability) before the signal peak occurs. When the signal peak occurs, the battery current is limited, but the speaker signal should still be clean because the boost capacitor can provide the remainder of the charge. The boost output may droop, but the amplified signal should still be clean as long as the droop is not large enough to eat into the headroom margin of the speaker driver. In this way, the hybrid class H / predictive class G amplifier architecture can provide much higher power for mid-to-high frequencies despite limited battery current. Furthermore, efficiency at low power is not compromised.

[0073]

[0082] The various operations of the methods described above may be performed by any suitable means capable of performing the corresponding functions, which may include various hardware component(s) and / or software component(s), including, but not limited to, circuits, application specific integrated circuits (ASICs), or processors, and / or various hardware module(s) and / or software module(s). Generally, when operations are illustrated in figures, the operations may have corresponding equivalent means-plus-function components that are similarly numbered.

[0074]

[0083] For example, the delaying means may include a delay element, such as delay element 402 as shown in Figure 4. The amplifying means may include an amplifier, such as amplifier 110 shown in Figure 1 or amplifier 408 shown in Figure 4. The power conditioning means may include a voltage regulator, such as boost converter 200 shown in Figure 2 or boost converter 406 depicted in Figure 4. The selectively controlling means may include control logic, such as control logic 404 shown in Figure 4.

[0075]

[0084] As used herein, the term "determining" encompasses a wide variety of actions. For example, "determining" may include calculating, computing, processing, deriving, investigating, searching (e.g., looking up in a table, database, or another data structure), ascertaining, and the like. "Determining" may also include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. "Determining" may also include resolving, selecting, choosing, establishing, and the like.

[0076]

[0085] As used herein, a phrase referring to "at least one of" a list of items refers to any combination of those items, including single members. By way of example, "at least one of a, b, or c" is intended to encompass a, b, c, ab, ac, bc, and abc, as well as any combination having multiples of the same element (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc, or any other permutation of a, b, and c).

[0077]

[0086] The methods disclosed herein include one or more steps or actions that achieve the described method. The steps and / or actions of those methods may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order of specific steps and / or actions and / or the use of those steps and / or actions may be modified without departing from the scope of the claims.

[0078]

[0087] It should be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes 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. The invention as described in the claims of the present application as originally filed is set forth below. [C1] 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; selectively controlling the boost converter to operate in at least one of a predicted class G mode or a class H mode based on a magnitude of the input signal; A method of amplification comprising: [C2] The method of C1, wherein the selectively controlling includes controlling the boost converter to operate in the predictive class-G mode when the magnitude 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. [C3] The method of C2, wherein controlling the boost converter to operate in the predictive class-G mode includes charging an output capacitor of the boost converter to a voltage higher than a peak value of the input signal before the peak value of the delayed version of the input signal is received by the amplifier. [C4] The method of C2, wherein the selectively controlling further comprises controlling the boost converter to operate in the Class H mode when the magnitude of the input signal is less than the first threshold and greater than a second threshold. [C5] The method of C4, wherein the selectively controlling further comprises controlling the boost converter to operate in a bypass mode when the magnitude of the input signal is less than the second threshold. [C6] The method of C2, wherein the selectively controlling further comprises controlling the boost converter to operate in the Class H mode when the magnitude of the input signal is less than the first threshold. [C7] The method of C2, wherein controlling the boost converter to operate in the predictive class-G mode includes modifying a reference voltage for the boost converter based on the magnitude of the input signal. [C8] The method of C1, wherein the predictive class G mode includes a multi-level predictive class G mode. [C9] 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; 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, the control logic being configured to selectively control the boost converter to operate in at least one of a predicted class G mode or a class H mode based on a magnitude of an input signal; An amplifier circuit comprising: [C10] 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; The amplifier circuit of C9, wherein the control logic is configured to control the boost converter to operate in the predictive class-G mode when the magnitude 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. [C11] 13. The amplifier circuit of claim 10, wherein the control logic 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 value of the input signal before the peak value of the delayed version of the input signal is received by the amplifier. [C12] The amplifier circuit of C10, wherein the control logic is configured to control the boost converter to operate in the Class H mode when the magnitude of the input signal is less than the first threshold and greater than a second threshold. [C13] The amplifier circuit of C12, wherein the control logic is configured to control the boost converter to operate in a bypass mode when the magnitude of the input signal is less than the second threshold. [C14] 13. The amplifier circuit of claim 10, wherein the control logic is configured to control the boost converter to operate in the Class H mode when the magnitude of the input signal is less than the first threshold. [C15] The amplifier circuit of C10, wherein the control logic is configured to modify a reference voltage for the boost converter operating in the predictive class G mode based on the magnitude of the input signal. [C16] The control logic further comprises: a class H controller having an input coupled to the second input of the control logic; a Class G controller having an input coupled to the first input of the control logic; 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; 10. The amplifier circuit of claim 9, comprising: [C17] The amplifier circuit of C16, wherein the multiplexer has one or more control inputs coupled to a set of outputs of the Class G controller. [C18] The amplifier circuit of C9, wherein the predicted class G mode includes a multi-level predicted class G mode. [C19] The amplifier circuit of C9, wherein the amplifier includes a speaker driver. [C20] 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; means for selectively controlling the means for adjusting power to operate in at least one of a predicted class-G mode or a class-H mode based on a magnitude of the input signal; 1. An apparatus for amplification comprising:

Claims

1. 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; selectively controlling, via control logic, the boost converter to operate in at least one of a predicted class G mode or a class H mode based on a magnitude 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; A method of amplification comprising:

2. 2. The method of claim 1 , wherein the selectively controlling comprises controlling the boost converter to operate in the predictive class-G mode when the magnitude 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. 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 value of the input signal before the peak value of the delayed version of the input signal is received by the amplifier.

4. 3. The method of claim 2, wherein the selectively controlling further comprises controlling the boost converter to operate in the Class H mode when the magnitude of the input signal is less than the first threshold and greater than a second threshold.

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

6. 3. The method of claim 2, wherein the selectively controlling further comprises controlling the boost converter to operate in the Class H mode when the magnitude of the input signal is less than the first threshold.

7. 3. The method of claim 2, wherein controlling the boost converter to operate in the predictive class G mode comprises modifying a reference voltage for the boost converter based on the magnitude 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. 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; 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, the control logic being configured to selectively control the boost converter to operate in at least one of a predicted class G mode or a class H mode based on a magnitude of an input signal; An amplifier circuit comprising:

10. 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; 10. The amplifier circuit of claim 9, wherein the control logic is configured to control the boost converter to operate in the predictive class-G mode when the magnitude 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. 11. The amplifier circuit of claim 10, wherein the control logic 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 value of the input signal before the peak value of the delayed version of the input signal is received by the amplifier.

12. 11. The amplifier circuit of claim 10, wherein the control logic is configured to control the boost converter to operate in the Class H mode when the magnitude of the input signal is less than the first threshold and greater than a second threshold.

13. 13. The amplifier circuit of claim 12, wherein the control logic is configured to control the boost converter to operate in a bypass mode when the magnitude of the input signal is less than the second threshold.

14. 11. The amplifier circuit of claim 10, wherein the control logic is configured to control the boost converter to operate in the class H mode when the magnitude of the input signal is less than the first threshold.

15. 11. The amplifier circuit of claim 10, wherein the control logic is configured to modify a reference voltage for the boost converter operating in the predictive class G mode based on the magnitude of the input signal.

16. The control logic further comprises: a class H controller having an input coupled to the second input of the control logic; a Class G controller having an input coupled to the first input of the control logic; 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; 10. The amplifier circuit of claim 9, comprising:

17. 17. The amplifier 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 amplifier circuit of claim 9 , wherein the predicted class-G mode comprises a multi-level predicted class-G mode.

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

20. 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 said means for amplifying; means for selectively controlling the means for adjusting power to operate in at least one of a predicted class-G mode or a class-H mode based on a magnitude of the input signal, the means for selectively controlling being configured to selectively control the means for adjusting power further based on the delayed version of the input signal; 1. An apparatus for amplification comprising:

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