Photoelectric Readout Gain Switching via Variable Resistor
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Solution Overview
Problem
Existing photoelectric conversion apparatuses face challenges in widening the range of input signals while maintaining a compact chip size, as methods involving multiple capacitive elements increase chip size.
Innovation Solution
A photoelectric conversion apparatus with a light receiving circuit, a readout circuit, a ΔΣ A/D converter, and a control circuit that changes the gain by adjusting the resistance value of a variable resistor in the readout circuit, allowing for dynamic gain adjustment without increasing chip size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple capacitive elements are used to hold signals for gain adjustment, then gain adjustment capability is improved, but chip size increases
Solution Approach 1:
The patent changes the resistance value of a single variable resistor to adjust gain, instead of changing the number of capacitive elements. This parameter change approach allows gain adjustment while maintaining a compact chip size, as only one resistor is used rather than multiple capacitors.
Solution Approach 2:
The patent extracts the gain adjustment function from the signal holding capacitors and implements it separately through a variable resistor in the readout circuit. This separation allows the capacitors to be minimized or removed while gain adjustment capability is maintained through the resistor-based approach.
2Adaptability or versatility
If the number of capacitive elements is increased to widen input signal range, then signal range is improved, but device complexity increases
Solution Approach 1:
The patent uses a variable resistor with adjustable resistance values to handle different input signal ranges, replacing the need for multiple capacitive elements with different capacitance values. This single component with variable parameters simplifies the device while maintaining versatility.
Solution Approach 2:
The variable resistor serves multiple functions: it adjusts gain, adapts to different input signal ranges, and works with the single capacitive element. This multi-functional component reduces the overall number of components needed in the circuit.
3Adaptability or versatility
If multiple capacitive elements are used for signal holding, then gain adjustment is improved, but manufacturing complexity increases
Solution Approach 1:
The patent extracts the gain adjustment function from the capacitive signal holding circuitry and implements it through a variable resistor in the readout circuit. This extraction simplifies manufacturing by reducing the number of capacitive elements that need to be precisely matched and assembled.
Solution Approach 2:
The patent implements gain adjustment through changing the resistance value of a single variable resistor, which is simpler to manufacture and control than coordinating multiple capacitive elements. The variable resistor can be adjusted via control signals without requiring complex manufacturing processes for multiple capacitor variants.
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
Enables flexible gain adjustment in accordance with different driving modes, improving the apparatus's ability to handle varying signal ranges without the need for additional capacitive elements, thus maintaining a compact design.
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.