Differential Transistor Control Unit for Photoelectric Conversion Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The accuracy of signal output from photoelectric conversion apparatuses is compromised due to significant voltage changes at the drain of differential transistors, which can lead to inversion of the output and reduce the accuracy of analog-to-digital conversion, especially when a common reference signal is shared among multiple differential amplifiers.
Innovation Solution
The introduction of a control unit within the output circuit that includes a current mirror circuit or other control elements to manage the voltage change at the drain of the differential transistor, thereby reducing the impact of voltage inversion and improving the accuracy of the signal output by controlling the change in the reference signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a differential transistor is used in the photoelectric conversion apparatus, then the analog-to-digital conversion can be performed by comparing voltages, but significant voltage changes at the drain of the differential transistor cause inversion of the output and reduce conversion accuracy
Solution Approach 1:
A control unit is introduced as an intermediary component between the differential transistor and the output circuit. This control unit monitors the drain voltage of the differential transistor and adjusts the reference signal to prevent voltage inversion, thereby maintaining conversion accuracy while preserving the ease of operation of the differential comparison method
Solution Approach 2:
The control unit implements a feedback mechanism by continuously monitoring the drain voltage of the differential transistor and dynamically adjusting the reference signal based on the detected voltage changes. This feedback loop prevents voltage inversion and ensures accurate analog-to-digital conversion without compromising the operational simplicity of the differential amplifier approach
2Device complexity
If a common reference signal is shared among multiple differential amplifiers, then device complexity is reduced, but voltage changes in one amplifier affect others and reduce overall accuracy
Solution Approach 1:
The control unit implements a feedback mechanism that monitors drain voltage changes in real-time and dynamically adjusts the reference signal to compensate for voltage variations caused by other differential amplifiers, maintaining high conversion accuracy while preserving the simplicity of the shared reference signal architecture
Solution Approach 2:
The control unit enables the reference signal to self-adjust in response to voltage changes in the system. By automatically compensating for interference from other differential amplifiers through real-time monitoring and adjustment, the system maintains accuracy without requiring separate reference signals for each amplifier, thus avoiding increased device 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 configuration enhances the accuracy of the digital signal output by minimizing the voltage change at the drain of the differential transistor, thereby reducing errors in analog-to-digital conversion and improving the overall performance of the photoelectric conversion apparatus.
Implementation Method 1
a signal based on an electric charge generated in a photoelectric conversion element is input
Data Source
Figure 1
Figure 2
Figure 3
AI summary
In a photoelectric conversion apparatus, a pixel transistor (M3) and a differential transistor (M5) form a differential pair. A clamp circuit (300) clamps a gate voltage of the differential transistor (M5). An output circuit (105) performs a first operation in which a voltage based on the voltage at the gate of a pixel transistor (M3) is output to the gate of the differential transistor (M5). The output circuit (105) also performs a second operation in which in response to receiving a current from the differential transistor (M5), a signal based on a result of a comparison between the gate voltage of the pixel transistor (M3) and the gate voltage of the differential transistor (M5) is output to the output node (310). In the second operation, a control unit in the output circuit (105) controls a change in the drain voltage of the differential transistor (M5) to be smaller than a change in the voltage at the output node (310).