Nonlinear power supply ramping for pop-click noise reduction

Patent metadata

Field	Value
Publication number	US-2016255451-A1
Application number	US-201514630994-A
Country	US
Kind code	A1
Filing date	Feb 25, 2015
Priority date	Feb 25, 2015
Publication date	Sep 1, 2016
Grant date	—

Abstract

A nonlinear power supply generator is provided that nonlinearly changes a power supply voltage for a circuit during power up of the circuit to reduce high-frequency noise in an output signal from the circuit.

First claim

We claim:

1 . A system comprising:
a driver configured to drive an output signal; and a nonlinear power supply voltage generator configured to nonlinearly change at least one power supply voltage for the driver from a first DC value during a power-off state for the driver to a second DC value during an active state for the driver.

2 . The system of claim 1 , wherein the driver comprises an audio driver and wherein the nonlinear power supply voltage generator is configured to nonlinearly change the at least one power supply voltage to reduce a pop and click noise produced by the audio driver upon transitioning from the power-off state to the active state.

3 . The system of claim 2 , wherein the nonlinear power supply voltage generator is configured to nonlinearly change the at least one power supply voltage according to a raised cosine function.

4 . The system of claim 2 , wherein the nonlinear power supply voltage generator is configured to nonlinearly change the at least one power supply voltage according a Gaussian function.

5 . The system of claim 2 , wherein the nonlinear power supply voltage generator is configured to change the at least one power supply voltage according to a piecewise linear function.

6 . The system of claim 2 , wherein the audio driver comprises a serial stack of a PMOS transistor and an NMOS transistor.

7 . The system of claim 2 , wherein the at least one power supply voltage comprises a positive power supply voltage and a negative power supply voltage, the system further comprising:
a positive charge pump for producing the positive power supply voltage; and a negative charge pump for producing the negative power supply voltage, wherein the nonlinear power supply voltage generator is configured to control the positive charge pump to nonlinearly change the positive power supply voltage and to control the negative charge pump to nonlinearly change the negative power supply voltage.

8 . The system of claim 2 , further comprising a processor configured to decode a digital audio signal according to a CODEC into at least one input signal for the audio driver, and wherein the processor is configured to implement the nonlinear power supply voltage using software.

9 . The system of claim 2 , wherein the nonlinear power supply generator comprises a state machine.

10 . The system of claim 6 , further comprising an averaging circuit configured to average the positive power supply voltage with the negative power supply voltage to produce an averaged input signal for the audio driver during a transition from the powered-off state to the active state.

11 . The system of claim 10 , wherein the averaging circuit comprises a voltage divider.

12 . The system of claim 11 , further comprising at least one switch configured to couple the voltage divider to a power supply rail for one of the positive and negative power supply voltages.

13 . The system of claim 12 , wherein the at least one switch is configured to close for a programmable duration during an onset of the nonlinear change for the positive and negative power supply voltages.

14 . A method, comprising:
during a powered-off state for an audio driver having a positive power supply node for carrying a positive power supply voltage, discharging the positive power supply voltage to a first DC value; and powering on the audio driver from the off state by nonlinearly increasing the positive power supply voltage from the first DC value to a second DC value.

15 . The method of claim 14 , wherein powering on the audio driver further comprises nonlinearly decreasing a negative power supply voltage from a third DC value to a fourth DC value.

16 . The method of claim 14 , wherein nonlinearly increasing the positive power supply voltage comprises increasing the positive power supply voltage according to a raised cosine function.

17 . The method of claim 14 , wherein nonlinearly increasing the positive power supply voltage comprises increasing the positive power supply voltage according to a Gaussian function.

18 . The method of claim 15 , further comprising: averaging the nonlinearly increasing positive power supply voltage with the nonlinearly decreasing negative power supply voltage to produce an input voltage signal for the audio driver during a transition from the powered-off state to an active mode for the audio driver.

19 . A system, comprising:
an audio driver configured to drive an output signal; and means for nonlinearly changing a positive power supply voltage for the audio driver from a first DC value during a power-off state for the audio driver to a second DC value during an active state for the audio driver.

20 . The system of claim 19 , further comprising a means for nonlinearly changing a negative power supply voltage for the audio driver from a third DC value during the power-off state for the audio driver to a fourth DC value during an active state for the audio driver.

Assignees

• Qualcomm Inc

Inventors

• Keskin Mustafa
• Sidiqi Khalid Junaid
• Hugunin Derick
• Jaffee James Ian
• Oliveira Louis Dominic

Classifications

• H03F3/3022

  CMOS common source output SEPP amplifiers (H03F3/3008 takes precedence) · CPC title

• H03F3/181

  Low-frequency amplifiers, e.g. audio preamplifiers · CPC title

• H04R3/00

  Circuits for transducers (arrangements for producing a reverberation or echo sound G10K15/08; amplifiers H03F) · CPC title

• H04R5/04

  Circuit arrangements, {e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments (combinations of amplifiers H03F3/68; stereophonic systems H04S)} · CPC title

• H04S1/005 Primary

  For headphones · CPC title