DAC Cell Error Correction for Amplitude and Timing Skew
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Solution Overview
Problem
Digital-to-analog converters (DACs) face performance limitations due to timing skew errors, which are not typically corrected, leading to reduced linearity and increased noise, especially at higher sampling and signal frequencies, requiring larger device sizes that increase area and power consumption.
Innovation Solution
A DAC configuration that includes a main DAC, a cell error determination circuit, and a correction DAC to calculate and correct skew and amplitude errors, allowing for reduced design requirements in matching and thus minimizing area and power consumption by using a small correction DAC to subtract errors from the main DAC output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If device size is increased to improve matching and reduce skew errors, then timing skew error performance is improved, but area and power consumption increase
Solution Approach 1:
The DAC is divided into multiple segments, with correction DACs dedicated to specific segments (e.g., MSB segment). This segmentation allows error correction to be applied locally to critical segments without requiring all DAC cells to be oversized, thus reducing total area while maintaining timing skew error performance.
Solution Approach 2:
A correction DAC is introduced as an intermediary component that generates correction signals to compensate for timing skew errors in the main DAC. This intermediary approach allows small correction signals to offset large timing skew errors without requiring the main DAC cells to be physically larger, resolving the contradiction between precision and area.
2Manufacturing precision
If device size is increased to improve matching and reduce skew errors, then timing skew error performance is improved, but power consumption increases
Solution Approach 1:
Power consumption is reduced by segmenting the DAC and applying correction only to critical segments (e.g., MSB) rather than uniformly increasing size across all DAC cells. The correction DAC consumes minimal power compared to oversizing the entire DAC array, thus improving timing skew error performance without proportional power increase.
Solution Approach 2:
The invention changes the approach from physical parameter scaling (increasing device size) to signal parameter manipulation (generating correction signals). The correction DAC manipulates signal parameters to compensate for timing skew errors, achieving the same precision improvement without the power consumption penalty of larger devices.
3Manufacturing precision
If correction DAC is added for error correction, then amplitude and skew error performance is improved, but device complexity increases
Solution Approach 1:
The correction DAC is merged with the existing DAC structure, sharing common components such as the switching matrix and output stage. This merging approach allows error correction functionality to be added without proportionally increasing overall device complexity, as many components serve dual purposes in both main DAC and correction DAC operations.
Solution Approach 2:
The correction DAC is designed with multi-functionality, serving both amplitude error correction and timing skew error correction through different operating modes or configurations. This universality reduces the need for separate correction circuits for each error type, thereby limiting the increase in device complexity while maintaining improved precision.
Data Source
AI summary
A digital-to-analog converter (DAC) and a method for correcting amplitude and/or skew error in a DAC. The DAC includes a main DAC, cell error determination circuit, a correction DAC, and a combiner. The main DAC includes a plurality of DAC cells. The cell error determination circuit is configured to determine an amplitude error and/or a skew error of each of the plurality of DAC cells and generate error data of the DAC based on the input data to the DAC cells. The correction DAC is configured to generate an error signal based on the error data. The combiner is configured to combine the error signal with an output of the main DAC.