Multi-Channel Driver Sequencing to Reduce Click and Pop Artefacts
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Solution Overview
Problem
Multi-channel audio and haptic driver systems experience artefacts such as audible clicks, pops, vibrations, or undesired movements due to transient voltages during state changes, particularly during start-up or shut-down, exacerbated by shared ground connections between output signal paths.
Innovation Solution
The implementation of sequencer circuitry that controls state changes in each output signal path to ensure they are not synchronized, along with the use of ground-referenced DACs and split-supply amplifier circuitry, and the inclusion of clamp paths to manage voltage transients, reduces the magnitude of artefacts by staggering the state changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If state changes in multiple output signal paths are synchronized, then system operation is simplified and efficient, but transient voltages from one path appear on other paths through common ground connections, causing audible artefacts such as clicks or pops
Solution Approach 1:
The sequencer circuitry performs preliminary actions by pre-planning and orchestrating the timing of state changes in each output signal path. It proactively schedules non-synchronized state changes before they occur, preventing transient voltage interference from propagating through the common ground connection to other channels, thus eliminating audible artefacts while maintaining systematic control
2Manufacturing precision
If calibration is performed using one-time programmable components to minimize offsets, then manufacturing precision is improved, but additional artefacts still occur due to voltage transients coupling through shared ground connections in multi-channel systems
Solution Approach 1:
The sequencer circuitry acts as an intermediary control mechanism that mediates between multiple output signal paths sharing a common ground connection. By introducing controlled timing delays and non-synchronized state changes, it prevents direct coupling of voltage transients between channels, thereby eliminating the harmful artefacts that calibration alone cannot prevent
Data Source
AI summary
Circuitry for driving first and second loads, the circuitry comprising: a first output signal path for supplying a first driving signal to the first load; a second output signal path for supplying a second driving signal to the second load; sequencer circuitry configured to initiate a first state change in the first output signal path and a second state change in the second output signal path, wherein the sequencer circuitry is configured to control the initiation of the first and second state changes such that the second state change is not synchronised with the first state change.