ΔΣ ADC Photoelectric Readout Gain Switching Without Larger Chips
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Solution Overview
Problem
Existing photoelectric conversion apparatuses face challenges in changing gain without increasing chip size, particularly when using sample-and-hold circuits with multiple capacitive elements, which can lead to larger chip sizes and reduced design flexibility.
Innovation Solution
Incorporating a control circuit that adjusts the resistance value of a variable resistor in the readout circuit to change the gain of the photoelectric conversion apparatus, allowing for dynamic gain adjustment without increasing chip size, and enabling the use of ΔΣ A/D converters with adjustable settings for improved accuracy and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If sample-and-hold circuits with multiple capacitive elements are used to change gain, then gain adjustment capability is improved, but chip size increases
Solution Approach 1:
The patent changes the resistance value of an existing variable resistor in the readout circuit to adjust gain, rather than adding multiple capacitive elements. This parameter change approach allows gain adjustment while maintaining the same chip area, as it utilizes the existing resistor structure instead of adding new components.
2Adaptability or versatility
If multiple capacitive elements are added to hold signals, then gain adjustment is enabled, but device complexity increases
Solution Approach 1:
The existing variable resistor in the readout circuit is made to serve multiple functions: it not only performs its original signal reading function but also enables gain adjustment when combined with the ΔΣ A/D converter. This multi-functionality approach avoids adding separate gain adjustment components, thereby reducing device complexity.
Solution Approach 2:
The patent merges the gain adjustment function with the existing readout circuit by utilizing the variable resistor already present in that circuit. Instead of creating a separate gain control circuit with multiple capacitive elements, the gain adjustment is combined with the signal reading function in a single integrated approach.
3Adaptability or versatility
If fixed gain design is used, then device complexity is reduced, but adaptability to different operating modes deteriorates
Solution Approach 1:
The patent introduces dynamic gain adjustment capability by making the resistor value variable and controllable. The control circuit can dynamically change the resistance value of the variable resistor to adjust gain according to different operating modes, transforming a static fixed-gain design into a dynamic adjustable-gain design without excessive complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for flexible gain adjustment in photoelectric conversion apparatuses, enhancing their performance and accuracy while maintaining a compact chip size, and improving the design freedom of the apparatus by enabling changes in gain based on different operating modes.
Implementation Method 1
a light receiving circuit configured to convert light into an electrical signal
Implementation Method 2
The readout circuit includes a variable resistor on a signal path for supplying the analog current signal to the ΔΣ A/D converter. The control circuit changes the gain of the photoelectric conversion apparatus by changing a resistance value of the variable resistor.
Data Source
AI summary
A photoelectric conversion apparatus includes a light receiving circuit configured to convert light into an electrical signal, a readout circuit configured to read out an analog signal corresponding to the electrical signal, a ΔΣ A/D converter configured to convert the analog signal into a digital signal, and a control circuit configured to change a gain of the photoelectric conversion apparatus in accordance with a change of a driving mode of the photoelectric conversion apparatus. The analog signal read out by the readout circuit is an analog current signal. The readout circuit includes a variable resistor on a signal path for supplying the analog current signal to the ΔΣ A/D converter. The control circuit changes the gain of the photoelectric conversion apparatus by changing a resistance value of the variable resistor.