Image Sensor Current Controller Stabilization Time
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Solution Overview
Problem
Image sensors face a challenge in reducing sampling time due to slow voltage drop rates at the output node, leading to increased stabilization duration and limited frame rates, primarily caused by low driving current and coupling noise during reset and transmission operations.
Innovation Solution
An image sensor design incorporating a current controller that adjusts the amount of current flowing through a sinking unit, using boosted and bias voltages to enhance driving current during signal generation and sampling, thereby shortening stabilization duration and reducing sampling time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the driving current is increased to speed up voltage drop at the output node, then the sampling time is reduced, but the power consumption increases
Solution Approach 1:
The patent applies dynamics by making the sinking current adjustable rather than fixed. The current controller dynamically changes the sinking current magnitude based on operational requirements, allowing high current during stabilization to reduce sampling time, and lower current during normal operation to reduce power consumption. This dynamic adjustment resolves the contradiction between speed and energy efficiency.
Solution Approach 2:
The patent changes the parameter of sinking current magnitude from a fixed value to a controllable variable. By adjusting the sinking current parameter according to different operational phases (stabilization vs. normal operation), the system achieves both fast stabilization when needed and low power consumption during steady state, resolving the time-energy tradeoff.
2Stability of the object's composition
If the stabilization duration is extended to ensure complete discharge of the output node, then the voltage stability is improved, but the frame rate is limited
Solution Approach 1:
The patent applies preliminary action by applying a strong sinking current before the sampling operation to pre-stabilize the output node voltage. This preliminary stabilization ensures that the output node is fully discharged and ready for the next sampling cycle, enabling faster frame rates while maintaining voltage stability. The strong current is applied in advance rather than during the entire operation.
Solution Approach 2:
The patent uses periodic action by applying high sinking current only during specific phases (reset and sampling) rather than continuously. The current controller periodically activates the strong sinking current to maintain voltage stability at critical moments, allowing the system to achieve high frame rates while ensuring stability when needed, rather than being constrained by continuous stabilization requirements.
3Duration of action of stationary object
If the sinking current is increased to speed up voltage changes, then the stabilization duration is reduced, but the noise coupling during reset and transmission operations increases
Solution Approach 1:
The patent applies local quality by making the sinking current strength location-specific in time. Different magnitudes of sinking current are applied at different operational stages: high current during reset and sampling when speed is critical, and reduced current during transmission when noise coupling must be minimized. This spatial-temporal differentiation of current strength resolves the contradiction between stabilization speed and noise reduction.
Data Source
AI summary
An image sensor for reducing a sampling time by shortening a stabilization duration is provided. The image sensor includes a pixel unit, a sampling unit sampling a signal from an output node of the pixel unit, a sinking unit sinking current from the output node of the pixel unit, and a current controller controlling the amount of current in the sinking unit.