CMOS Image Sensor Amplifier Circuit for Faster Pixel Settling
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Solution Overview
Problem
CMOS Image Sensors face challenges in reducing power consumption and pixel settling time, which affects the frame rate due to significant pixel load contributions to total power consumption and the need for sufficient time for pixel voltage to settle during reset and signal readout phases.
Innovation Solution
An amplifier circuit provides a configurable voltage supply to ensure pixel loads track the pixel reset voltage, reducing power consumption and increasing frame rate by minimizing pixel settling time through variable resistor configuration in Analog to Digital Converter source follower circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pixel load current is increased to reduce pixel settling time, then frame rate increases, but power consumption increases
Solution Approach 1:
The patent changes the voltage parameter at pixel loads by introducing a configurable voltage supply that can set pixel load voltages to track pixel reset voltages. This parameter change allows the system to achieve faster settling without increasing current, thereby resolving the contradiction between frame rate and power consumption
Solution Approach 2:
The patent introduces an intermediary voltage control mechanism that mediates between the pixel circuits and the readout amplifier. By controlling the voltage at pixel loads through this intermediary, the system can achieve faster settling times without the need to increase pixel load current, thus reducing power consumption while maintaining high frame rate
2Use of energy by moving object
If pixel load current is decreased to reduce power consumption, then power consumption decreases, but pixel settling time increases
Solution Approach 1:
The patent changes the voltage parameter at pixel loads by introducing a configurable voltage supply that can set pixel load voltages to track pixel reset voltages. This parameter change allows the system to achieve faster settling without increasing current, thereby resolving the contradiction between frame rate and power consumption
Solution Approach 2:
The patent applies preliminary action by pre-configuring the voltage at pixel loads before the readout phase. The configurable voltage supply sets the pixel load voltages in advance to match the expected reset voltages, so when readout occurs, the settling time is minimized without requiring high current
3Use of energy by moving object
If configurable voltage supply is implemented to track pixel reset voltage, then power consumption decreases and frame rate increases, but device complexity increases
Solution Approach 1:
The configurable voltage supply is designed to serve multiple functions: it provides voltage tracking for pixel loads, enables power consumption reduction, and supports frame rate enhancement. This multi-functionality justifies the added complexity by delivering multiple benefits from a single circuit addition
Solution Approach 2:
The voltage supply implements feedback mechanisms where pixel reset voltages are monitored and used to adjust the configurable voltage outputs. This feedback ensures accurate voltage tracking while maintaining system stability, making the added complexity manageable and effective
Data Source
AI summary
A Complementary Metal Oxide Semiconductor (CMOS) Image Sensor (CIS), includes a pixel circuit, a VSL circuit, and an amplifier. The pixel circuit may generate a reset voltage and a signal voltage, based on a power supply connected to the pixel circuit and/or intensity of light captured by the pixel circuit. The VSL circuit may store pixel information in a pixel load based on settling a voltage at the pixel load to the signal voltage and/or set the voltage at the pixel load to a pixel reset voltage based on settling the voltage at the pixel load to the reset voltage. The amplifier may generate a voltage, based on varying a resistance at an input of the amplifier, to enable the VSL circuit to store the pixel information and/or set the voltage at the pixel load to the pixel reset voltage.