Hybrid DAC Driver with Segmented R-2R Lower Stage

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Solution Overview

Problem

Non-uniformity in DAC units leads to degradation of linearity in analog output signals, causing signal distortions and complicating calibration and correction processes, especially in high-fidelity applications like audio and video transmission.

Innovation Solution

A hybrid DAC driver structure is introduced, comprising an upper DAC stage with non-uniformly weighted units and a lower DAC stage formed in an R-2R resistor ladder network, ensuring uniformity and linearity in the analog output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If non-uniform DAC units are used in the upper DAC stage, then the device complexity is reduced and manufacturing is simplified, but the linearity of the analog output signal deteriorates

Engineering Contradiction:

ImproveDAC unit uniformity requirementVSAvoidoutput signal linearity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The DAC is divided into two separate stages: an upper DAC stage with non-uniform units (simpler manufacturing) and a lower DAC stage with uniform R-2R units (ensures linearity). Each stage handles different portions of the digital signal, allowing the benefits of both uniform and non-uniform designs to coexist without compromising overall performance.

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

If non-uniform DAC units are used, then calibration and correction processes become more complex, but the initial design and manufacturing become simpler

Engineering Contradiction:

ImproveDAC unit fabricationVSAvoidcalibration process complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

By segmenting the DAC into upper and lower stages with different unit uniformity characteristics, the calibration complexity is managed through the inherent linearity of the R-2R lower stage, which requires minimal calibration while the upper stage benefits from simplified manufacturing.

Inventive Principle:

Principle #1Segmentation

3Manufacturing precision

If uniform R-2R resistor ladder network is used in the lower DAC stage, then the linearity and accuracy of the analog output is improved, but the device complexity increases

Engineering Contradiction:

Improveanalog output linearityVSAvoidDAC structure complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The lower DAC stage specifically employs uniform R-2R units where linearity is critical for accurate analog reconstruction, while the upper DAC stage uses non-uniform units where manufacturing simplicity is prioritized. This localized application of uniformity where needed optimizes the balance between precision and complexity.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20250125815A1Hybrid DAC-based driver structure

Publication Date: 2025.04.17 SAMSUNG ELECTRONICS CO LTD

AI summary

A hybrid digital-to-analog converter (DAC) driver is provided. The hybrid DAC driver includes an upper DAC stage configured to receive an upper set of bits of a digital signal, the upper DAC stage comprising an upper set of DAC units, with a first DAC unit in the upper set of DAC units having a different weight than a second DAC unit in the upper set of DAC units; a lower DAC stage configured to receive a lower set of bits of the digital signal, the lower DAC stage comprising a lower set of DAC units formed in an R-2R resistor ladder network; and an output stage for outputting an analog signal from the upper DAC stage and the lower DAC stage.