DAC Digital Pre-Distortion for Reference Ripple Mitigation
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Solution Overview
Problem
High-speed communication systems using digital-to-analog converters (DACs) face challenges with distortion due to timing and amplitude mismatches, which conventional methods fail to address effectively without increasing power consumption and hardware complexity.
Innovation Solution
The implementation of a transition aware dynamic element matching (DEM) scheme with a constant transition rate (CTR-DEM) in DACs, combined with digital pre-distortion techniques, to mitigate distortion caused by signal and switching currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional distortion mitigation approaches are used in DACs, then timing and amplitude errors are addressed, but power consumption increases and hardware complexity increases
Solution Approach 1:
The patent applies digital pre-distortion by modifying the digital input signal before it reaches the DAC to preemptively compensate for expected distortion. The distortion compensation circuit calculates corrected signal values based on predicted distortion characteristics, allowing the DAC to produce accurate output without requiring complex post-processing or feedback mechanisms, thus reducing power consumption while maintaining distortion mitigation effectiveness
2Reliability
If conventional distortion mitigation approaches are used in DACs, then timing and amplitude errors are addressed, but hardware complexity increases
Solution Approach 1:
The patent introduces a distortion compensation circuit as an intermediary component between the digital signal source and the DAC. This circuit performs digital pre-distortion calculations and modifies the input signal to compensate for anticipated distortion, eliminating the need for complex analog correction circuits or feedback mechanisms within the DAC itself, thereby reducing overall hardware complexity while maintaining effective distortion mitigation
3Object-generated harmful factors
If signal current distortion is reduced, then power supply ripple decreases, but signal-to-noise ratio must be maintained
Solution Approach 1:
The patent modifies the digital input signal parameters through pre-distortion processing to compensate for distortion caused by signal current. By adjusting the digital signal values in advance based on predicted distortion characteristics, the system reduces power supply ripple effects while maintaining the correct signal-to-noise ratio at the DAC output, as the pre-distorted signal inherently accounts for ripple-induced variations
Data Source
AI summary
A system includes a first circuit configured to provide a digitally pre-distorted input signal, a digital-to-analog converter including a number of unit elements, a digital input, and a digital output. Each unit element is configured to receive a reference voltage and to be controllable by a control signal provided in response to the digitally pre-distorted input signal. The digital-to-analog converter provides an analog output. The first circuit is configured to reduce distortion due to signal dependent changes to the reference voltage. The signal dependent changes can be due at least in part to current through the supply network that supplies the reference voltage. The digital to analog converter can be a voltage mode converter.