# US 2017/0250655 A1 · Dynamic volume management in audio amplifiers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0250655 A1 - Document ID: US20170250655A1 - Status: Published application - Kind: A1 - Application number: 15/444,021 - Filed: 2017-02-27 - Published: 2017-08-31 - Earliest claimed: 2016-02-29 - Assignees: QUALCOMM Incorporated - Applicants: QUALCOMM Incorporated - Inventors: William COPE; Jieting SUN; Donald GEE - Web page: https://patentgrep.com/patent/US20170250655A1 ## CPC - H03F 1/0233: {by using a signal derived from the output signal, e.g. bootstrapping the voltage supply} - H03F 1/523: {for amplifiers using field-effect devices (H03F1/526 takes precedence)} - H03F 3/185: with field-effect devices (H03F3/187 takes precedence) - H03F 3/2173: {of the bridge type} - H03G 7/002: {in untuned or low-frequency amplifiers, e.g. audio amplifiers (H03G7/007, H03G7/001, H03G7/008, H03G7/02, H03G7/06 take precedence)} - H03G 7/08: incorporating negative feedback - H04R 3/007: {Protection circuits for transducers} - H03F 3/217: Class D power amplifiers; Switching amplifiers - H03F 3/2171: {with field-effect devices (H03F3/2173 - H03F3/2178 take precedence)} - H03F 2200/03: the amplifier being designed for audio applications - H03F 2200/351: Pulse width modulation being used in an amplifying circuit - H03F 2200/391: the output circuit of an amplifying stage comprising an LC-network - H03F 2200/426: the amplifier comprising circuitry for protection against overload - H04R 2430/01: Aspects of volume control, not necessarily automatic, in sound systems - H03F: AMPLIFIERS - H03G: CONTROL OF AMPLIFICATION - H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K) ## Abstract Certain aspects of the present disclosure provide an amplifier for signal amplification. Certain aspects further describe methods and apparatus for applying overload protection for such amplifier. For example, one method generally includes detecting an overload condition of an amplifier based on a signal at a node of the amplifier, and controlling a parameter of an input signal of the amplifier such that the parameter of the input signal is maintained below a threshold based on the detection of the overload condition. The parameter of the input signal may include, for example, a voltage level or a duty cycle of the input signal. ## Claims ### Claim 1 A method for overload protection, comprising: detecting an overload condition of an amplifier based on a signal at a node of the amplifier; and controlling a parameter of an input signal of the amplifier such that the parameter of the input signal is maintained at or below a first threshold based on the detection of the overload condition. ### Claim 2 (depends on 1) The method of claim 1, wherein the signal at the node comprises the input signal, and wherein the parameter of the input signal comprises a duty cycle of the input signal. ### Claim 3 (depends on 1) The method of claim 1, wherein the node comprises an input node of an output stage of the amplifier, an input node of one or more drivers configured to drive the input node of the output stage, or an output node of the output stage of the amplifier. ### Claim 4 (depends on 1) The method of claim 1, wherein the signal at the node comprises a pulse-width modulation (PWM) signal, and wherein the overload condition of the amplifier is detected based on a duty cycle of the PWM signal. ### Claim 5 (depends on 1) The method of claim 1, wherein detecting the overload condition is further based on at least one of the input signal or a feedback signal of the amplifier. ### Claim 6 (depends on 1) The method of claim 1, further comprising: adjusting a value of a counter based on the detection; and comparing the value of the counter to a second threshold, wherein controlling the input signal is performed in response to the value of the counter exceeding the second threshold. ### Claim 7 (depends on 6) The method of claim 6, wherein detecting the overload condition comprises comparing a duty cycle of the signal at the node with a third threshold. ### Claim 8 (depends on 7) The method of claim 7, wherein adjusting the value of the counter comprises: incrementing the counter if the duty cycle exceeds the third threshold; and decrementing the counter if the duty cycle does not exceed the third threshold. ### Claim 9 (depends on 7) The method of claim 7, wherein controlling the parameter of the input signal comprises decreasing a voltage of the input signal until the value of the counter no longer exceeds the second threshold. ### Claim 10 (depends on 9) The method of claim 9, wherein controlling the parameter of the input signal further comprises increasing the voltage of the input signal if the value of the counter no longer exceeds the second threshold. ### Claim 11 (depends on 1) The method of claim 1, wherein the signal at the node of the amplifier comprises a power supply voltage of the amplifier, and wherein detecting the overload condition is based on a rate of change of the power supply voltage. ### Claim 12 (depends on 1) The method of claim 1, wherein controlling the parameter of the input signal comprises preventing a voltage level of the input signal from exceeding the first threshold until the overload condition is no longer detected. ### Claim 13 (depends on 12) The method of claim 12, further comprising decreasing the voltage level of the input signal until the overload condition is no longer detected. ### Claim 14 (depends on 13) The method of claim 13, wherein decreasing the voltage level of the input signal comprises decreasing the voltage level of the input signal periodically. ### Claim 15 An apparatus for signal amplification, comprising: an amplifier configured to generate an amplified signal based on an input signal; and a circuit coupled to a node of the amplifier and configured to: detect an overload condition of the amplifier based on a signal at the node; and control a parameter of the input signal of the amplifier such that the parameter of the input signal is maintained at or below a first threshold based on the detection of the overload condition. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein the signal at the node comprises the input signal, and wherein the parameter of the input signal comprises a duty cycle of the input signal. ### Claim 17 (depends on 15) The apparatus of claim 15, wherein the node comprises an input node of an output stage of the amplifier, an input node of one or more drivers configured to drive the input node of the output stage, or an output node of the output stage of the amplifier. ### Claim 18 (depends on 15) The apparatus of claim 15, wherein the signal at the node comprises a pulse-width modulation (PWM) signal, and wherein the circuit is configured to detect the overload condition of the amplifier based on a duty cycle of the PWM signal. ### Claim 19 (depends on 15) The apparatus of claim 15, wherein the circuit is further configured to detect the overload condition based on at least one of the input signal or a feedback signal of the amplifier. ### Claim 20 (depends on 15) The apparatus of claim 15, wherein the circuit is further configured to: adjust a value of a counter based on the detection; and compare the value of the counter to a second threshold, wherein the circuit is configured to control the parameter of the input signal in response to the value of the counter exceeding the second threshold. ### Claim 21 (depends on 20) The apparatus of claim 20, wherein the circuit is further configured to detect the overload condition by comparing a duty cycle of the input signal with a third threshold. ### Claim 22 (depends on 21) The apparatus of claim 21, wherein the circuit is configured to adjust the value of the counter by: incrementing the counter if the duty cycle exceeds the third threshold; and decrementing the counter if the duty cycle does not exceed the third threshold. ### Claim 23 (depends on 21) The apparatus of claim 21, wherein the circuit is configured to control the parameter of the input signal by decreasing a voltage of the input signal until the value of the counter no longer exceeds the second threshold. ### Claim 24 (depends on 23) The apparatus of claim 23, wherein the circuit is configured to control the parameter of the input signal by increasing the voltage of the input signal if the value of the counter no longer exceeds the second threshold. ### Claim 25 (depends on 15) The apparatus of claim 15, further comprising: a power supply, wherein the signal at the node comprises a power supply voltage generated by the power supply to power an output stage of the amplifier, wherein the circuit is configured to detect the overload condition based on a rate of change of the power supply voltage. ### Claim 26 (depends on 15) The apparatus of claim 15, wherein the circuit is configured to control the parameter of the input signal by preventing a voltage level of the input signal from exceeding the first threshold until the overload condition is no longer detected. ### Claim 27 (depends on 26) The apparatus of claim 26, wherein the circuit is further configured to decrease the voltage level of the input signal until the overload condition is no longer detected. ### Claim 28 (depends on 27) The apparatus of claim 27, wherein the circuit is configured to decrease the voltage level of the input signal periodically. ### Claim 29 An apparatus for signal amplification, comprising: means for generating an amplified signal based on an input signal; means for detecting an overload condition of the means for generating based on a signal at a node of the means for generating; and means for controlling a parameter of the input signal such that the parameter of the input signal is maintained at or below a threshold based on the detection of the overload condition. ### Claim 30 (depends on 29) The apparatus of claim 29, wherein the signal at the node comprises the input signal and wherein the parameter of the input signal comprises a duty cycle of the input signal.