Digital Pre-Distortion for DAC Harmonic and Noise Control
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Solution Overview
Problem
High-speed digital-to-analog converters (DACs) face challenges with timing and amplitude mismatches, leading to increased power consumption and hardware complexity, while conventional distortion mitigation techniques fail to address harmonic effects effectively.
Innovation Solution
The implementation of a transition aware dynamic element matching (DEM) scheme with a constant transition rate, which determines the number and selection of DAC unit elements to switch, reducing power consumption and mitigating harmonic distortion by enforcing a consistent error profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional distortion mitigation techniques are used in high-speed DACs, then timing and amplitude errors are addressed, but power consumption increases and hardware complexity increases while harmonic effects are not addressed
Solution Approach 1:
The patent changes the parameter of transition rate from variable to constant, enforcing a constant transition rate for DAC unit elements. This parameter change simplifies the control logic while maintaining distortion mitigation effectiveness and addressing harmonic effects, thereby reducing hardware complexity without sacrificing timing and amplitude accuracy.
Solution Approach 2:
The patent segments the distortion mitigation function into two independent parts: (1) constant transition rate control for reducing harmonic distortion, and (2) dynamic element matching for addressing timing and amplitude errors. This segmentation allows each function to be optimized independently, reducing overall hardware complexity while maintaining both timing/amplitude accuracy and harmonic distortion reduction.
2Measurement precision
If conventional distortion mitigation techniques are used in high-speed DACs, then timing and amplitude errors are addressed, but power consumption increases
Solution Approach 1:
The patent changes the transition rate parameter from variable to constant, which reduces the switching activity of DAC unit elements. This parameter change directly reduces dynamic power consumption while maintaining the timing and amplitude accuracy through dynamic element matching, as the constant transition rate prevents excessive switching without compromising distortion mitigation.
3Measurement precision
If dynamic element matching is implemented without constant transition rate control, then timing and amplitude mismatches are mitigated, but harmonic distortion is not addressed and noise floor remains high
Solution Approach 1:
The patent segments the distortion mitigation function into two independent parts: (1) constant transition rate control for reducing harmonic distortion, and (2) dynamic element matching for addressing timing and amplitude errors. This segmentation allows each function to be optimized independently, reducing overall hardware complexity while maintaining both timing/amplitude accuracy and harmonic distortion reduction.
Solution Approach 2:
The patent changes the parameter of transition rate from variable to constant, enforcing a constant transition rate for DAC unit elements. This parameter change simplifies the control logic while maintaining distortion mitigation effectiveness and addressing harmonic effects, thereby reducing hardware complexity without sacrificing timing and amplitude accuracy.
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.