CMOS Image Sensor ADC Gain Selection Without Column Amplifiers

Solution Overview

Problem

Conventional CMOS image sensors require a large number of amplifiers for gain selection, leading to increased chip area and power consumption, and potential gain accuracy issues due to production tolerance.

Innovation Solution

An analog-digital converter design that eliminates the need for amplifiers as gain selecting sections by using a comparator and latch section with a gain selecting switch and adjustable analog ramp signals, allowing gain selection without multiple amplifiers, thereby reducing chip area and power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If amplifiers are used as gain selecting sections for each column, then gain selection capability is achieved, but chip area and power consumption increase

Engineering Contradiction:

Improvegain selection capabilityVSAvoidchip area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent extracts the gain selection function from individual column amplifiers and relocates it to a shared amplifier circuit. By removing the need for multiple amplifiers with gain selection capabilities and replacing them with a single amplifier that receives control signals, the chip area is significantly reduced while maintaining gain selection functionality across all columns.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The shared amplifier circuit serves multiple columns simultaneously by receiving gain selection control signals. This universal amplifier performs the gain selection function for all columns rather than requiring dedicated amplifiers for each column, achieving multi-functionality that reduces overall circuit complexity and area.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If amplifiers are used as gain selecting sections for each column, then gain selection capability is achieved, but power consumption increases

Engineering Contradiction:

Improvegain selection capabilityVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by stationary object

Solution Approach 1:

The patent extracts the gain selection function from individual column amplifiers and relocates it to a shared amplifier circuit. By removing the need for multiple amplifiers with gain selection capabilities and replacing them with a single amplifier that receives control signals, the chip area is significantly reduced while maintaining gain selection functionality across all columns.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The shared amplifier circuit serves multiple columns simultaneously by receiving gain selection control signals. This universal amplifier performs the gain selection function for all columns rather than requiring dedicated amplifiers for each column, achieving multi-functionality that reduces overall circuit complexity and area.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If multiple amplifiers are used for gain selection, then gain selection is possible, but gain accuracy deteriorates due to production tolerance

Engineering Contradiction:

Improvegain selection capabilityVSAvoidgain accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent extracts the gain selection function from individual column amplifiers and relocates it to a shared amplifier circuit. By removing the need for multiple amplifiers with gain selection capabilities and replacing them with a single amplifier that receives control signals, the chip area is significantly reduced while maintaining gain selection functionality across all columns.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the control parameter from physical amplifier configuration to electrical control signals. By using control signals to select gain values in a shared amplifier rather than relying on multiple physically different amplifiers, the system achieves more consistent gain accuracy不受 production tolerance variations affecting multiple amplifier units.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS7741988B2Analog-digital converter, solid-state image capturing apparatus, and electronic information device

Publication Date: 2010.06.22 RS TECH CO LTD

AI summary

An analog-digital converter is provided. The analog-digital converter includes: a comparing section for comparing an input signal voltage and an analog ramp voltage in which a voltage level gradually increases; and a latch section for storing a digital value of a digital ramp signal, in which a digital value of a voltage level gradually increases in synchronization with the analog ramp voltage when the analog ramp voltage or a voltage corresponding to the analog ramp voltage and the input signal voltage are equal. A voltage in which part or all of a plurality of analog ramp signals are added is used as the analog ramp voltage so that a gain is selectable.