Audio Codec Circuit De-Pop Switch for Noise Prevention

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Solution Overview

Problem

Conventional audio codec circuits often cause pop-noise in speakers due to the active amplifier's floating signal input terminals and noise reception from capacitive or inductive effects when entering power saving mode or turning off.

Innovation Solution

The audio codec circuit incorporates a de-pop switch and control circuit to maintain signal and common-mode voltage terminals at fixed voltage levels, preventing floating and noise reception by coupling them to ground or reference voltages, thereby ensuring continuous operation without erroneous signal output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the audio codec circuit enters power saving mode or turns off power, then energy consumption is reduced, but the active amplifier's signal input terminals become floating and generate pop-noise

Engineering Contradiction:

Improvepower consumptionVSAvoidpop-noise

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary action by controlling the de-pop switch to connect the signal input terminal to a fixed voltage (ground or reference voltage) before the audio codec circuit enters power saving mode or turns off. This preliminary voltage stabilization prevents the terminal from becoming floating, thereby eliminating the cause of pop-noise generation while allowing the power saving operation to proceed.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces a de-pop switch as an intermediary component between the signal input terminal and the fixed voltage terminal. This switch acts as a mediator that connects the terminal to a stable voltage reference when needed, preventing direct exposure to floating conditions and noise from capacitive or inductive effects, thus resolving the contradiction between power saving and noise prevention.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If the signal input terminal is left floating during power saving mode, then the audio codec circuit can save energy, but the terminal receives noises from capacitive coupling or inductance effects

Engineering Contradiction:

Improveenergy savingVSAvoidnoise reception

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The de-pop switch serves as an intermediary that connects the signal input terminal to a fixed voltage terminal during power saving mode. This intermediary connection prevents the terminal from being exposed to harmful noise from capacitive coupling or inductance effects, while allowing the audio codec circuit to maintain its power saving state.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies preliminary anti-action by proactively connecting the signal input terminal to a fixed voltage through the de-pop switch before the power saving mode fully engages. This preliminary protective action counteracts the potential harmful effects of floating terminals and noise reception, enabling energy saving without compromising signal integrity.

Inventive Principle:

Principle #9Preliminary anti-action

3Duration of action of stationary object

If the active amplifier remains in normal operating status during power saving mode, then signal processing continuity is maintained, but the amplifier outputs erroneous signals due to floating input terminals

Engineering Contradiction:

Improveoperational continuityVSAvoidsignal accuracy

Core Design Contradiction:

Duration of action of stationary objectVSReliability

Solution Approach 1:

The patent applies preliminary action by controlling the de-pop switch to connect the signal input terminal to a fixed voltage before the audio codec circuit enters power saving mode. This ensures the terminal is properly biased even when the amplifier remains active, preventing erroneous signal output and maintaining signal accuracy throughout the power saving transition.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The de-pop switch control circuit provides feedback control by monitoring the power saving mode status and automatically adjusting the de-pop switch state accordingly. When power saving mode is detected, the control circuit activates the de-pop switch to stabilize the input terminal voltage, ensuring continuous reliable operation of the amplifier without erroneous signals.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS10820095B2Audio codec circuit capable of avoiding pop-noise

Publication Date: 2020.10.27 REALTEK SEMICON CORP

AI summary

An audio codec circuit includes: an audio processing circuit; an output driver circuit for generating an analog output signal based on the output of the audio processing circuit; an analog signal pin for outputting the analog output signal to an active amplifier; a multifunction signal pin for providing different signal transmission functionalities according to the configuration of the audio processing circuit; at least one de-pop switch arranged between the analog signal pin and a first fixed-voltage terminal or between the multifunction signal pin and a second fixed-voltage terminal; and a de-pop switch control circuit, coupled with the audio processing circuit and the at least one de-pop switch, arranged to operably control the at least one de-pop switch based on the instruction from the audio processing circuit.