AFE Circuit DC Voltage Restoration Without Capacitors

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Solution Overview

Problem

Conventional analog front-end (AFE) circuits in display systems face challenges with delayed reflection of DC voltage level changes in analog image signals due to AC-coupling and clamping, and designing input buffers with high impedance is difficult.

Innovation Solution

An image processing device with no capacitors or clamps, utilizing analog-to-digital converters (ADCs) and compensation circuits to generate digital signals, allowing for immediate reflection of DC voltage changes and flexible buffer design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If AC-coupling and clamping are used to restore DC voltage levels of analog image signals, then the DC voltage levels can be restored, but the restored DC voltage levels take time to settle and cannot reflect immediate changes

Engineering Contradiction:

ImproveDC voltage level restoration accuracyVSAvoidTime for DC voltage level to settle

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent removes the AC-coupling capacitor and clamper circuit from the signal path, extracting the problematic components that caused delay. By directly coupling the analog image signal to the ADC input and using a digital domain clamper, the circuit eliminates the settling time issue while maintaining DC voltage level restoration capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the analog clamper circuit (electrical/mechanical system) with a digital domain clamper implemented in the ADC or subsequent digital processing. This substitution allows immediate reflection of DC voltage level changes without the physical settling time inherent in analog capacitor-based clamping circuits

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Stability of the object's composition

If input buffers are installed to buffer restored DC voltage levels and prevent running, then DC voltage stability is improved, but the design of input buffers with high input impedance becomes difficult

Engineering Contradiction:

ImproveDC voltage level stabilityVSAvoidInput buffer design complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent removes the traditional input buffer with high input impedance requirement by directly coupling the analog signal to the ADC. The ADC's inherent input characteristics provide sufficient buffering without requiring complex high-impedance buffer design, thereby simplifying the circuit while maintaining signal integrity

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a direct coupling path as an intermediary between the analog image signal source and the ADC, eliminating the need for complex input buffers. This direct path maintains signal integrity while avoiding the design challenges of high-impedance buffering

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If capacitors and clamps are used in the AFE circuit, then AC-coupling and clamping functions are achieved, but the component count, power consumption, and size increase

Engineering Contradiction:

ImproveAC-coupling and clamping functionVSAvoidComponent count

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent removes physical capacitors and clamper components from the AFE circuit, extracting the AC-coupling and clamping functions to the digital domain. This elimination reduces component count, power consumption, and circuit size while maintaining the essential signal processing functions through digital techniques

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces physical capacitor-based AC-coupling and analog clamper circuits with digital domain implementations. The ADC and subsequent digital processing perform the equivalent functions without requiring physical capacitors or analog clamping components, thereby reducing the bill of materials and power consumption

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 approach enables immediate reflection of DC voltage level changes and reduces component count, power consumption, and size, while improving image quality by eliminating the need for capacitors and clamps.

Implementation Method 1

an analog-to-digital converter and includes no clampers

Methodology Applied

Scientific EffectAnalog-to-digital conversion:

Data Source

PatentUS8130422B2Image processing device and method thereof

Publication Date: 2012.03.06 REALTEK SEMICON CORP

AI summary

An image processing device is provided which comprises an input unit and an analog front end circuit with DC inputs. According to the invention, no capacitor is installed in the input unit and no clamper is installed in the AFE circuit with DC inputs. By appropriately selecting a comparing voltage and adding a level shifter or a compensation circuit, the invention can still generate an accurate digital signal.