Image Sensor DC Bias Removal via Adjustable Reference Voltage
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Solution Overview
Problem
Image sensors face challenges in effectively distinguishing actual signals from background signals caused by background light, requiring high-resolution analog-to-digital converters to achieve satisfactory signal quality.
Innovation Solution
An image sensor system comprising a pixel array, sense amplifier, analog-to-digital converter, processor, and voltage generator, where the sense amplifier uses a reference voltage to remove direct current bias from pixel signals, allowing the processor to adjust the voltage and enable the gain amplifier to enhance the signal range without needing high-bit number converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-resolution (high bit number) analog-to-digital converter is used to convert images, then the signal quality and ability to identify actual sensing signals is improved, but the device complexity and cost increase
Solution Approach 1:
The patent extracts and removes the DC bias voltage component from the pixel signal using a sense amplifier with adjustable reference voltage. By separating the DC component (which contains background light information) from the AC component (which contains actual image signals), the system can use a lower-resolution ADC while maintaining signal identification accuracy, thus resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The patent dynamically adjusts the reference voltage parameter of the sense amplifier to match the background light level. By changing the reference voltage parameter based on feedback from the ADC, the system optimizes the signal range for conversion, enabling standard ADCs to achieve sufficient precision without requiring high-bit converters, thereby reducing device complexity while maintaining measurement precision
2Adaptability or versatility
If the reference voltage is adjusted to match background light levels, then the signal range for standard ADCs is improved, but the need for additional control circuitry increases
Solution Approach 1:
The patent implements a feedback mechanism where the processor receives digital signals from the ADC, determines the background light level, and generates a feedback signal to adjust the reference voltage accordingly. This closed-loop feedback system enables the image sensor to adapt to different background light conditions and optimize signal range for standard ADCs, achieving high adaptability while using only standard components without requiring complex additional circuitry
Data Source
AI summary
An image sensor is provided. The image sensor includes a pixel array, a sense amplifier, an analog-to-digital converter, a processor and a voltage generator. The sense amplifier obtains a first signal according to a pixel signal from the pixel array and a reference voltage, wherein the reference voltage has a first voltage level. The analog-to-digital converter converts the first signal into a first digital signal. The processor provides a feedback signal according to the first digital signal. The voltage generator adjusts the reference voltage to a second voltage level corresponding to the feedback signal. The sense amplifier removes a direct current (DC) bias voltage from the pixel signal according to the reference signal having the second voltage level.