Display Output Buffer Circuit for Nonlinear Offset Compensation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The existing display driving apparatus suffers from non-linear distortion in output voltage due to offsets in the interpolation section, degrading the reliability of the display driving apparatus.

Innovation Solution

An output buffer circuit is designed with a decoder to convert interpolation data into control data for inverse compensation, using a bias current generated by digital-to-analog conversion for the control data to produce accurate output voltage by adjusting the positive and negative currents accordingly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If a bias current is generated by digital-to-analog conversion for interpolation data to perform linear interpolation, then the area occupied by the DAC is reduced, but non-linear distortion occurs in the output voltage due to offset

Engineering Contradiction:

ImproveDAC areaVSAvoidoutput voltage accuracy

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The patent inverts the conventional approach by generating the bias current through resistive division of reference voltages rather than through digital-to-analog conversion of interpolation data. This inversion eliminates the offset-induced non-linear distortion while maintaining area efficiency, as the resistive divider network occupies less area than a full DAC would require.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the parameter control method from direct digital control of bias current to analog voltage division control. By adjusting the resistance ratios in the divider network, the bias current is controlled to vary non-linearly in a way that compensates for the offset, thereby improving output voltage accuracy without requiring a large DAC.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If linear interpolation is performed using bias current controlled by digital-to-analog conversion, then the circuit complexity is reduced, but non-linear distortion degrades reliability

Engineering Contradiction:

Improveinterpolation circuit complexityVSAvoiddisplay driving apparatus reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent replaces the digital-to-analog conversion mechanism with a passive resistive voltage division mechanism. This substitution eliminates the complex DAC circuitry while achieving the desired current control through simple resistor networks, thereby reducing circuit complexity and improving reliability by removing the source of non-linear distortion.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces reference voltages and resistive divider networks as intermediary elements between the digital control signals and the bias current generation. These intermediaries enable smooth analog control of the bias current without requiring direct digital-to-analog conversion, simplifying the circuit while maintaining reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution effectively compensates for non-linear distortion caused by offsets, ensuring an accurate output voltage corresponding to display data and improving the reliability of the output buffer circuit.

Implementation Method 1

a decoder configured to receive interpolation data and output control data obtained by decoding the interpolation data

Methodology Applied

Scientific EffectDigital decoding and inverse compensation:

Implementation Method 2

an output circuit configured to generate a bias current having the amount of current non-linearly varying in response to a change in a value of the control data by digital-to-analog conversion for the control data

Methodology Applied

Scientific EffectDigital-to-analog conversion:

Implementation Method 3

an output stage configured to output an output voltage having a level determined by pull-up based on the positive current and the first feedback current and pull-down based on the negative current and the second feedback current

Methodology Applied

Scientific EffectElectrical current control for voltage regulation:

Data Source

PatentUS11308843B2Output buffer circuit for display driving apparatus

Publication Date: 2022.04.19 SILICON WORKS CO LTD

AI summary

Disclosed is an output buffer circuit for a display driving apparatus, which generates an output voltage by using a bias current controlled by digital-to-analog conversion for interpolation data, the output buffer circuit including a decoder configured to output control data obtained by decoding interpolation data, and an output circuit configured to output an output voltage by using a bias current having the amount of current controlled by digital-to-analog conversion for the control data.