# US 2013/0154736 A1 · Transient Signal Suppression for a Class-D Audio Amplifier Arrangement > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0154736 A1 - Document ID: US20130154736A1 - Status: Published application - Kind: A1 - Application number: 13/329,699 - Filed: 2011-12-19 - Published: 2013-06-20 - Earliest claimed: 2011-12-19 - Assignees: Broadcom Corporation - Inventors: Xicheng JIANG; Minsheng Wang - Web page: https://patentgrep.com/patent/US20130154736A1 ## CPC - H03F 1/305: {in case of switching on or off of a power supply} - H03F 3/217: Class D power amplifiers; Switching amplifiers - H03G 3/348: {Muting in response to a mechanical action or to power supply variations, e.g. during tuning; Click removal circuits} - H03F: AMPLIFIERS - H03G: CONTROL OF AMPLIFICATION ## Abstract A Class-D amplifier arrangement is disclosed that implements an auxiliary feedback loop and a primary feedback loop. The auxiliary feedback loop operates upon an input signal when the Class-D amplifier arrangement is operating under a power-up condition and a power-down condition so that a modulated signal is confined within the auxiliary feedback loop during the power-up condition and the power-down condition. The confinement of the modulated signal within the auxiliary feedback loop during the power-up condition and the power-down condition diverts transient signals coupled onto the modulated signal from an output device. The primary feedback loop operates upon the input signal when the Class-D amplifier arrangement is operating under a normal condition so that the modulated signal is introduced to the output device during the normal condition. ## Claims ### Claim 1 A Class-D amplifier arrangement, comprising: an auxiliary feedback loop configured to operate upon an input signal when the Class-D amplifier arrangement is operating under a power-up condition and a power-down condition, wherein a modulated signal is confined within the auxiliary feedback loop during the power-up condition and the power-down condition so that a plurality of transient signals coupled on the modulated signal is diverted away from an output device; and a primary feedback loop configured to operate upon the input signal when the Class-D amplifier arrangement is operating under a normal condition, wherein the modulated signal is introduced to the output device during the normal condition. ### Claim 2 (depends on 1) The Class-D amplifies arrangement of claim 1, further comprising: an auxiliary driver included in the auxiliary feedback loop, the auxiliary driver configured to operate at a maximized gain when the Class-D amplifier arrangement is operating under the power-up condition and the power-down condition and to operate at a minimized gain when the Class-D amplifier arrangement is operating under the normal condition. ### Claim 3 (depends on 2) The Class-D amplifier arrangement of claim 2, further comprising: a power driver included in the primary feedback loop, the power driver configured to operate at the minimized gain when the Class-D amplifier arrangement is operating under the power-up condition and the power-down condition and to operate at the maximized gain when the Class-D amplifier arrangement is operating under the normal condition. ### Claim 4 (depends on 3) The Class-D amplifier of claim 3, wherein the power driver is further configured to: operate as an open circuit when operating at the minimized gain to divert the modulated signal from reaching the output device, thereby preventing the plurality of transient signals from reaching the output device; and allow the primary feedback loop to operate on the input signal when operating at the maximized gain to introduce the modulated signal to the output device. ### Claim 5 (depends on 2) The Class-D amplifier of claim 2, wherein the auxiliary driver is further configured to: operate as an open circuit when operating at the minimized gain to allow the primary feedback loop to operate on the input signal to introduce the modulated signal to the output device; and allow the auxiliary feedback loop to operate on the input signal when operating at the maximized gain to divert the modulated signal away from the output device, thereby preventing the plurality of transient signals coupled to the modulated signal from reaching the output device. ### Claim 6 (depends on 5) The Class-D amplifier of claim 5, wherein the auxiliary driver is further configured to operate at the maximized gain while the power driver is operating at the minimized gain and the power driver is further configured to operate at the maximized gain while the auxiliary driver is operating at the minimized gain. ### Claim 7 (depends on 6) The Class-D amplifier of claim 6, wherein the auxiliary driver is further configured to transition from the minimized gain to the maximized gain and/or from the maximized gain to the minimized gain based on a smooth ramp function. ### Claim 8 (depends on 6) The Class-D amplifier of claim 6, wherein the power driver is further configured to transition from the minimized gain to the maximized gain and/or from the maximized gain to the minimized gain based on the smooth ramp function. ### Claim 9 (depends on 8) The Class-D amplifier of claim 8, wherein the transition from the maximized gain to the minimized gain and/or the minimized gain to the maximized gain is programmable. ### Claim 10 (depends on 6) The Class-D amplifier of claim 6, wherein the auxiliary driver is further configured to ramp up to the maximized gain as the power driver is ramping down to the minimized gain and the power driver is further configured to ramp up to the maximized gain as the auxiliary driver is ramping down to the minimized gain. ### Claim 11 (depends on 1) The Class-D amplifier of claim 1, wherein the Class-D amplifier is further configured to transition from the power-up mode to the normal mode when a plurality of common components that is shared by the auxiliary feedback loop and the primary feedback loop is settled. ### Claim 12 (depends on 1) The Class-D amplifier of claim 1, wherein the Class-D amplifier is further configured to transition from the normal mode to the power-down mode when the plurality of common components that is shared by the auxiliary feedback loop and the primary feedback loop is settled. ### Claim 13 (depends on 10) The Class-D amplifier of claim 10, wherein the modulated signal increases as the auxiliary driver is ramping down to the minimized gain and the power driver is ramping up to the maximized gain. ### Claim 14 (depends on 13) The Class-D amplifier of claim 13, wherein an output signal provided by the output device increases as the modulated signal increases and decreases as the modulates signal decreases. ### Claim 15 A method for preventing a plurality of transient signals that couple onto a modulated signal from being introduced to an output device, comprising: (a) operating upon an input signal with an auxiliary feedback loop during a power-up condition and a power-down condition; (b) confining the modulated signal to the auxiliary feedback loop during the power-up condition and the power-down condition; (c) diverting away the plurality of transient signals coupled onto the modulated signal away from the output device during the power-up and power-down condition; (d) operating upon the input signal with a primary feedback loop during the normal condition; and (e) introducing the modulated signal to the output device during the normal condition. ### Claim 16 (depends on 15) The method of claim 15, wherein step (a) further comprises: (a)(i) introducing the input signal to the auxiliary feedback loop when an auxiliary driver included in the auxiliary feedback loop is operating at a maximized gain; and (a)(ii) removing the input signal from the primary feedback loop when a power driver included in the primary feedback loop is operating at a minimized gain. ### Claim 17 (depends on 15) The method of claim 15, wherein step (d) further comprises: (d)(i) introducing the input signal to the primary feedback loop when the power driver included in the primary feedback loop is operating at the maximized gain; and (d)(ii) removing the input signal from the auxiliary feedback loop when the auxiliary driver included in the auxiliary feedback loop is operating at the minimized gain. ### Claim 18 (depends on 17) The method of claim 17, further comprising: (f) transitioning from the power-up condition to the normal condition based on the auxiliary driver transitioning from the maximized gain to the minimized gain based on a smooth ramp function and the operating driver transitioning from the minimized gain to the maximized gain based on the smooth ramp function; and (g) transitioning from the normal condition to the power-down condition based on the operating driver transitioning from the maximized gain to the minimized gain based on the smooth ramp function and the auxiliary driver transitioning from the minimized gain to the maximized gain based on the smooth ramp function. ### Claim 19 (depends on 18) The method of claim 18, further wherein steps (f) and (g) further comprise: (f)(i) ramping down the auxiliary driver to the minimized condition as the power driver is ramping up to the maximized condition when transitioning into the normal condition; and (g)(i) ramping up the auxiliary driver to the maximized condition as the power driver is ramping down to the minimized condition when transitioning into the power-down condition. ### Claim 20 (depends on 19) The method of claim 19, wherein steps (f) and (g) further comprise: (f)(ii) transitioning from the power-up condition to the normal condition when a plurality of common components that is shared by the auxiliary feedback loop and the primary feedback loop is settled; and (g)(ii) transitioning from the normal condition to the power-down condition when the plurality of common components that is shared by the auxiliary feedback loop and the primary feedback loop is settled.