Audio Driver Power-State Control to Prevent Transition Artifacts
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Solution Overview
Problem
Prior art audio driver designs for HD audio codecs lack effective power management, leading to the creation of unpleasant audible audio artifacts due to limited power states and inability to handle power transitions efficiently.
Innovation Solution
A driver controller with a state machine and output switch provides a low impedance path to ground during transitions, decoupling the output signal from the driver amplifier to prevent unwanted audio artifacts by enabling power management across multiple states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If power management is implemented with limited power states (full power and shutdown only), then power consumption is reduced, but audio artifacts are generated during transitions
Solution Approach 1:
The power management system is segmented into multiple intermediate power states between full power and shutdown. Instead of directly transitioning between extreme states, the driver controller implements gradual power reduction through defined states (e.g., active, standby, mute), allowing smooth transitions that prevent audio artifacts while maintaining energy efficiency.
Solution Approach 2:
The output switch is activated in advance during transition periods to provide a low impedance path to ground before the actual power state change occurs. This preliminary action prepares the circuit to handle transient signals properly, preventing audio artifacts from being generated during the power management transition.
2Device complexity
If direct transition between full power and shutdown is implemented, then device complexity is reduced, but audio artifacts are created during transitions
Solution Approach 1:
An output switch is introduced as an intermediary component between the driver amplifier and the load. During transition periods, this switch provides a controlled low impedance path to ground, mediating the power state changes and preventing direct coupling of transient signals that would otherwise create audio artifacts.
Solution Approach 2:
The output switch is activated in advance during transition periods to provide a low impedance path to ground before the actual power state change occurs. This preliminary action prepares the circuit to handle transient signals properly, preventing audio artifacts from being generated during the power management transition.
3Object-generated harmful factors
If multiple power states are implemented with proper transition control, then audio artifacts are eliminated, but device complexity increases
Solution Approach 1:
The output switch serves multiple functions: it provides a low impedance path to ground during transitions, decouples the output signal from the driver amplifier during power state changes, and helps define different power states. This multi-functionality reduces the need for additional dedicated components, thereby limiting the increase in device complexity.
Solution Approach 2:
The power management control logic is merged with the existing driver controller structure. The state machine integrates power state management with the audio signal processing functions, combining multiple responsibilities into a unified control architecture that minimizes additional complexity.
Data Source
AI summary
A driver controller comprising a state machine for controlling transitions between a plurality of states. An output switch for providing a low impedance path to ground during transition periods. An output stage for decoupling output signal from driver amplifier during the transition periods.