Multi-Voltage Row Driver Circuitry for Image Sensors

Solution Overview

Problem

Conventional multi-voltage row drivers in image sensors require large level shifters that occupy significant circuit area and consume high power, especially in global shutter pixels where all row drivers are simultaneously activated, leading to inefficient power management and potential voltage drops.

Innovation Solution

A multi-voltage row driver circuit that utilizes fewer level shifters by employing a configuration with only two level shifting circuits and associated transistors to generate multiple voltage levels, reducing the overall area and power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional row drivers use large level shifters to generate multiple voltage levels, then the imaging performance is improved, but the circuit area and power consumption increase significantly

Engineering Contradiction:

Improveimaging performanceVSAvoidcircuit area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent merges the functions of multiple level shifters into a single level shifter circuit. Instead of using separate level shifters for each voltage level (Vhi, Vlo, Vaa, Vss), the invention uses one level shifter that can generate all four voltage levels by selectively connecting different transistor gates to appropriate voltage sources. This consolidation reduces the total circuit area occupied by level shifting functionality.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The level shifter circuit is designed with multi-functionality to generate multiple voltage levels (Vhi, Vlo, Vaa, Vss) using a single circuit structure. The level shifter can be configured to output different voltage levels by selectively activating different transistor switches, making it a universal voltage generation unit that replaces what would traditionally require multiple dedicated level shifters.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If conventional row drivers use large level shifters to generate multiple voltage levels, then the imaging performance is improved, but the power consumption increases significantly

Engineering Contradiction:

Improveimaging performanceVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The patent merges the functions of multiple level shifters into a single level shifter circuit. Instead of using separate level shifters for each voltage level (Vhi, Vlo, Vaa, Vss), the invention uses one level shifter that can generate all four voltage levels by selectively connecting different transistor gates to appropriate voltage sources. This consolidation reduces the total circuit area occupied by level shifting functionality.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The level shifter circuit is designed with multi-functionality to generate multiple voltage levels (Vhi, Vlo, Vaa, Vss) using a single circuit structure. The level shifter can be configured to output different voltage levels by selectively activating different transistor switches, making it a universal voltage generation unit that replaces what would traditionally require multiple dedicated level shifters.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If all row drivers are simultaneously activated in global shutter pixels, then the charge transfer operation is improved, but the power consumption and voltage drops are exacerbated

Engineering Contradiction:

Improvecharge transfer operationVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by stationary object

Solution Approach 1:

The patent merges the functions of multiple level shifters into a single level shifter circuit. Instead of using separate level shifters for each voltage level (Vhi, Vlo, Vaa, Vss), the invention uses one level shifter that can generate all four voltage levels by selectively connecting different transistor gates to appropriate voltage sources. This consolidation reduces the total circuit area occupied by level shifting functionality.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The level shifter circuit is designed with multi-functionality to generate multiple voltage levels (Vhi, Vlo, Vaa, Vss) using a single circuit structure. The level shifter can be configured to output different voltage levels by selectively activating different transistor switches, making it a universal voltage generation unit that replaces what would traditionally require multiple dedicated level shifters.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10785437B2Area and power efficient multi-voltage row driver circuitry for image sensors

Publication Date: 2020.09.22 SEMICON COMPONENTS IND LLC

AI summary

Image sensor pixels may receive row control signals for row driver circuitry. The row driver circuitry may include a plurality of row driver circuits each of which is capable of outputting row control signals at more than two power supply voltage levels. A row driver circuit may include only two level shifting circuits. A first level shifting circuit may control a first pull-up path operable to drive the row driver output to a first power supply voltage level and may also control a second pull-up path operable to drive the row driver output to a second power supply voltage level. A second level shifting circuit may control a first pull-down path operable to drive the row driver output to a third power supply voltage level and may also control a second pull-down path operable to drive the row driver output to a fourth power supply voltage level.