DAC Distortion Pre-Compensation for Component Mismatch Errors
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Solution Overview
Problem
Digital-to-analog converters (DACs) face performance issues due to mismatches in circuit components, such as rise/fall asymmetry, current amplitude mismatches, and timing offsets, which lead to distortion and affect signal quality, particularly in high-speed applications where existing techniques like dynamic element matching and mapping algorithms are complex and power-intensive.
Innovation Solution
The proposed solution involves optimizing DAC architectures by minimizing statistical error metrics through the use of weighted current sources with weights configured to minimize glitch errors, amplitude mismatches, and timing offsets, and applying digital pre-compensation using a distortion model characterized by parameters that correct for circuit component mismatches, thereby improving signal-to-noise distortion ratio (SNDR).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dynamic element matching and mapping algorithms are used to compensate for DAC component mismatches, then distortion is reduced and signal quality is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent changes the parameters of the current sources by applying scaling factors to adjust their amplitudes. This allows compensation for component mismatches by modifying the electrical parameters (current amplitude) rather than redesigning the entire DAC architecture or adding complex control logic.
Solution Approach 2:
The patent replaces complex mechanical/control systems (dynamic element matching algorithms and mapping techniques) with a simpler mathematical approach using scaling factors. Instead of implementing complex digital signal processing algorithms, the solution uses straightforward parameter multiplication to achieve distortion compensation.
2Reliability
If dynamic element matching and mapping algorithms are used to compensate for DAC component mismatches, then distortion is reduced and signal quality is improved, but power consumption increases
Solution Approach 1:
The patent modifies the operational parameters of the current sources by applying scaling factors. This parameter adjustment approach avoids the need for power-intensive digital signal processing algorithms while achieving the same distortion compensation effect, thereby reducing power consumption.
Solution Approach 2:
The patent extracts and compensates for the dominant source of distortion (component mismatches) separately from the main DAC operation. By identifying and correcting only the specific mismatch errors through scaling factors, the system avoids the overhead of comprehensive error correction algorithms that would consume more power.
3Reliability
If segmented DAC architectures are used to reduce component mismatches, then signal quality is improved, but the number of switches and device complexity increase
Solution Approach 1:
Instead of increasing the number of switches and segments, the patent achieves improved signal quality by changing the parameters (amplitudes) of the existing current sources. This parameter adjustment approach provides distortion compensation without requiring additional circuit elements or increased device complexity.
Solution Approach 2:
The patent inverts the conventional approach: instead of adding more segments and switches to reduce mismatches, it applies scaling factors to the existing current sources to compensate for mismatches. This reverse engineering approach achieves the same goal with fewer components.
Data Source
AI summary
An apparatus comprises circuitry configured to generate a predicted error signal by applying to a digital signal a distortion model characterized by parameters configured to model circuit component mismatches in a digital-to-analog converter (DAC), circuitry configured to generate a pre-compensated digital signal using the digital signal and the predicted error signal, and circuitry configured to provide the pre-compensated digital signal to the DAC for conversion into an analog signal.