# US 11,908,310 B2 · Methods and systems for detecting and managing unexpected spectral content in an amplifier system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,908,310 B2 - Document ID: US11908310B2 - Status: Granted - Kind: B2 - Application number: 17/549,399 - Filed: 2021-12-13 - Published: 2022-12-22 - Granted: 2024-02-20 - Earliest claimed: 2021-06-22 - Assignees: Cirrus Logic, Inc. - Applicants: Cirrus Logic International Semiconductor Ltd. - Inventors: Dana J. Taipale; Jon D. Hendrix; Emmanuel A. Marchais - Web page: https://patentgrep.com/patent/US11908310B2 ## CPC - G08B 6/00: Tactile signalling systems, e.g. tactile personal calling systems - G08B: SIGNALLING SYSTEMS, e.g. PERSONAL CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS ## Abstract A method may include receiving, by a transducer driving system, a first signal for driving an amplifier that drives an electromagnetic load and receiving, by the transducer driving system, a second signal driven by the amplifier in order to control a feedback loop of the transducer driving system. The method may also include detecting unexpected spectral content in the second signal, declaring an indicator event based on the detected unexpected spectral content, determining whether the indicator event occurs in an undesired pattern, and in response to the indicator event occurring in the undesired pattern, modifying a behavior of the transducer driving system. ## Claims ### Claim 1 A method comprising: receiving, by a transducer driving system, a first signal for driving an amplifier that drives an electromagnetic load; receiving, by the transducer driving system, a second signal driven by the amplifier in order to control a feedback loop of the transducer driving system; detecting unexpected spectral content in the second signal; declaring an indicator event based on the detected unexpected spectral content; determining whether the indicator event occurs in an undesired pattern; in response to the indicator event occurring in the undesired pattern, modifying a behavior of the transducer driving system. ### Claim 2 (depends on 1) The method of claim 1, wherein modifying the behavior of the transducer driving system comprises modifying a negative impedance of the feedback loop. ### Claim 3 (depends on 1) The method of claim 1, wherein modifying the behavior of the transducer driving system comprises modifying the negative impedance of the feedback loop for a duration of time which is a function of the undesired pattern. ### Claim 4 (depends on 3) The method of claim 3, wherein the negative impedance is modified for a fixed period of time. ### Claim 5 (depends on 3) The method of claim 3, wherein the negative impedance is modified for a dynamically-adjustable time which is a function of a history of indicator events. ### Claim 6 (depends on 1) The method of claim 1, wherein modifying the behavior of the transducer driving system comprises tuning a gain of a negative impedance of the feedback loop. ### Claim 7 (depends on 6) The method of claim 6, further comprising reducing the gain of the negative impedance to limit frequency of occurrence of indicator events. ### Claim 8 (depends on 1) The method of claim 1, wherein modifying the behavior of the transducer driving system comprises modifying a signal gain of the first signal. ### Claim 9 (depends on 8) The method of claim 8, further comprising reducing the signal gain to limit frequency of occurrence of instability events. ### Claim 10 A method comprising: receiving, by a transducer driving system, a first signal for driving an amplifier that drives an electromagnetic load; receiving, by the transducer driving system, a second signal driven by the amplifier in order to control a feedback loop of the transducer driving system; detecting unexpected spectral content in the second signal; in response to detecting the unexpected spectral content, modifying a system behavior of the transducer driving system by: monitoring the unexpected spectral content and the second signal for patterns that identify a physical damage of the electromagnetic load; and modifying a signal gain applied to the first signal to protect the transducer driving system. ### Claim 11 (depends on 10) The method of claim 10, wherein the patterns comprise a correlation between unexpected spectral content events and signal peaks of the second signal and the method further comprises dynamically modifying the signal gain to reduce the signal peaks. ### Claim 12 (depends on 10) The method of claim 10, wherein the patterns comprise a correlation between instability events and a signal duration of the second signal; and the method further comprises dynamically modifying the signal gain to reduce signal strength for long-duration signals. ### Claim 13 A transducer driving system, comprising: a driver output for driving an amplifier that drives an electromagnetic load; a feedback input for receiving a signal driven by the amplifier in order to control a feedback loop of the transducer driving system; and an unexpected spectral content detector and controller subsystem configured to: detect unexpected spectral content in the signal; declare an indicator event based on the detected unexpected spectral content; determine whether the indicator event occurs in an undesired pattern; and in response to the indicator event occurring in the undesired pattern, modify a behavior of the transducer driving system. ### Claim 14 (depends on 13) The transducer driving system of claim 13, wherein modifying the behavior of the transducer driving system comprises modifying a negative impedance of the feedback loop. ### Claim 15 (depends on 14) The transducer driving system of claim 14, wherein modifying the behavior of the transducer driving system comprises modifying the negative impedance of the feedback loop for a duration of time which is a function of the undesired pattern. ### Claim 16 (depends on 15) The transducer driving system of claim 15, wherein the negative impedance is modified for a fixed period of time. ### Claim 17 (depends on 15) The transducer driving system of claim 15, wherein the negative impedance is modified for a dynamically-adjustable time which is a function of a history of indicator events. ### Claim 18 (depends on 13) The transducer driving system of claim 13, wherein modifying the behavior of the transducer driving system comprises tuning a gain of a negative impedance of the feedback loop. ### Claim 19 (depends on 18) The transducer driving system of claim 18, wherein the unexpected spectral content detector and controller subsystem is further configured to reduce the gain of the negative impedance to limit frequency of occurrence of indicator events. ### Claim 20 (depends on 13) The transducer driving system of claim 13, wherein modifying the behavior of the transducer driving system comprises modifying a signal gain of a first signal. ### Claim 21 (depends on 20) The transducer driving system of claim 20, wherein the unexpected spectral content detector and controller subsystem is further configured to reduce the signal gain to limit frequency of occurrence of instability events. ### Claim 22 A transducer driving system comprising: a driver output for driving an amplifier that drives an electromagnetic load; a feedback input for receiving a first signal driven by the amplifier in order to control a feedback loop of the transducer driving system; and an unexpected spectral content detector and controller subsystem configured to: detect unexpected spectral content in the signal; and in response to detecting the unexpected spectral content, modify a system behavior of the transducer driving system by: monitoring the unexpected spectral content and a second signal for patterns that identify a physical damage of the electromagnetic load; and modifying a signal gain applied to the first signal to protect the transducer driving system. ### Claim 23 (depends on 22) The transducer driving system of claim 22, wherein the patterns comprise a correlation between unexpected spectral content events and signal peaks of the second signal and the method further comprises dynamically modifying the signal gain to reduce the signal peaks. ### Claim 24 (depends on 22) The transducer driving system of claim 22, wherein the patterns comprise a correlation between instability events and a signal duration of the second signal; and the method further comprises dynamically modifying the signal gain to reduce signal strength for long-duration signals.