Dynamic Bit-Cell Matching Network for DAC Distortion Control
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Solution Overview
Problem
Existing digital-to-analog converters (DACs) introduce distortion in audio signals due to component mismatches during production, leading to undesirable artifacts like popping and clicking, which are consistent for a given input signal.
Innovation Solution
A continuously variable dynamic element matching network (CVBP DEM) is employed to dynamically adjust the bit-cell population and activation pattern, using a combination of variable and fixed DEMs to minimize distortion by randomly selecting bit-cells and evenly distributing their activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fixed bit-cell activation is used in DACs, then manufacturing simplicity is maintained, but distortion and audio artifacts occur due to component mismatches
Solution Approach 1:
The patent implements dynamic element matching by making the bit-cell activation pattern variable over time rather than fixed. The system dynamically selects which bit-cells are activated in each clock cycle, ensuring that over time all bit-cells are used evenly. This dynamic approach converts consistent distortion from mismatched components into time-varying pseudorandom noise that can be filtered, thereby resolving the contradiction between manufacturing simplicity and distortion reduction.
Solution Approach 2:
The system changes the activation parameter of bit-cells from a static on/off state to a time-varying state where each bit-cell's activation duration and timing are modified. By controlling the population of active bit-cells and their activation patterns dynamically, the system transforms deterministic distortion into stochastic noise characteristics that are less perceptible and filterable.
2Object-generated harmful factors
If dynamic element matching with variable bit-cell population is implemented, then distortion is reduced by converting it to pseudorandom noise, but device complexity increases
Solution Approach 1:
The patent segments the bit-cell population into multiple groups or subsets that can be independently controlled and activated. By dividing the total bit-cell population into manageable segments and cycling through different activation patterns, the system achieves dynamic element matching without requiring complete reconfiguration of all bit-cells each cycle, thereby reducing the practical complexity while maintaining distortion reduction benefits.
Solution Approach 2:
The system employs periodic activation patterns where bit-cells are cycled through active and inactive states in regular intervals. This periodic action ensures that over time each bit-cell is activated for an equal duration, achieving population balance and distortion conversion to noise. The regular periodic structure simplifies control logic compared to fully random activation, reducing device complexity while maintaining effectiveness.
Data Source
AI summary
This disclosure relates to a system for mitigating distortion in a signal, including a plurality of bit-cells, a calculation circuit configured to determine a bit-cell population that is available to be activated for a given clock cycle, a dynamic element matching network configured to activate a subset of bit-cells of the bit-cell population, and a controller configured to control a pattern of activation of the subset of bit-cells of the bit-cell population.