Image Sensor Interface for Parasitic Capacitance Suppression

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Solution Overview

Problem

Conventional image sensors suffer from signal distortion due to parasitic capacitance effects in buses and input offset voltages of operational amplifiers, which affect the quality of reset and image signals.

Innovation Solution

An interface is designed with operational amplifiers and switches to connect capacitors between power supplies and input terminals during sampling and evaluation phases, canceling the effects of parasitic capacitance and offset voltages, and converting signals to reduce distortion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional buses are used to transmit reset and image signals, then the signal transmission path is simple, but parasitic capacitance causes signal distortion

Engineering Contradiction:

Improvesignal qualityVSAvoidparasitic capacitance effect

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces compensation capacitors that utilize the parasitic capacitance effect in reverse - by adding controlled capacitive elements with opposite polarity charges, the harmful parasitic capacitance is converted into a beneficial compensation mechanism that cancels out the distortion effects on reset and image signals

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Power

If operational amplifiers are used for signal conversion, then signal amplification and conversion are achieved, but input offset voltage causes output signal distortion

Engineering Contradiction:

Improvesignal amplification capabilityVSAvoidoutput signal accuracy

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent applies preliminary anti-action by introducing compensation capacitors that are pre-charged with opposite polarity voltages before the operational amplifier processing. This preliminary counter-voltage action prevents the offset voltage from causing distortion in the final output signal, thereby maintaining signal accuracy while preserving amplification capability

Inventive Principle:

Principle #9Preliminary anti-action

3Manufacturing precision

If high resolution images are produced with many pixels, then image quality is improved, but the complexity of signal processing increases

Engineering Contradiction:

Improveimage resolutionVSAvoidsignal processing complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the signal processing into distinct phases - sampling phase where reset and image signals are separately captured, and evaluation phase where they are sequentially processed through operational amplifiers. This segmentation allows high-resolution signals from many pixels to be processed systematically, reducing overall processing complexity while maintaining image quality

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8488032B2Image sensors, interfaces and methods capable of suppressing effects of parasitic capacitances

Publication Date: 2013.07.16 SAMSUNG ELECTRONICS CO LTD

AI summary

An interface capable of suppressing parasitic capacitance effects includes an array of switches switched in response to a switching signal. The interface suppresses effects of parasitic capacitance included in a bus, which transmits a reset signal and an image signal output from an image sensor. The suppressed parasitic capacitance effects suppress distortion of a digital image signal.