Image Sensor Ramp Voltage Circuit for Stable Stepped Waveforms
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Solution Overview
Problem
Current image sensing devices face challenges in generating stable ramp voltages with stepped waveforms, which are crucial for efficient image capture, particularly in integrating analog and digital control circuits within a single integrated circuit.
Innovation Solution
The proposed image sensing device employs a ramp voltage generation circuit that includes two source ramp voltage generation circuits and a ramp voltage generation circuit, utilizing switching elements to generate a ramp voltage with a voltage level between two source ramp voltages, adjusted in coarse and fine periods with controlled phase and voltage differences, to produce a stable stepped waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single source ramp voltage generation circuit is used, then the device complexity is reduced, but the stability and precision of the ramp voltage waveform deteriorates
Solution Approach 1:
The voltage generation circuit is divided into two independent source ramp voltage generation circuits (first and second) that each generate ramp voltages with different characteristics. These segmented circuits work in parallel to compensate for individual limitations, with the first circuit providing a baseline ramp voltage and the second circuit providing a corrected ramp voltage, thereby improving overall waveform stability while keeping each individual circuit relatively simple.
Solution Approach 2:
The patent changes key parameters of the ramp voltage including voltage level, period duration, and waveform shape by switching between different source ramp voltages generated by the two circuits. The control circuit dynamically adjusts which source ramp voltage is applied based on detected waveform characteristics, enabling parameter optimization to achieve stable stepped waveforms without increasing overall system complexity.
2Productivity
If the ramp voltage period is shortened to enable high-speed operation, then the productivity is improved, but the precision of voltage adjustment deteriorates
Solution Approach 1:
The system performs preliminary characterization of different source ramp voltage waveforms and pre-determines the optimal voltage source to use for each operating condition. The control circuit stores information about which source ramp voltage produces the most stable waveform at different period durations, allowing it to quickly switch to the appropriate source without requiring complex real-time adjustments, thus maintaining precision during high-speed operation.
Solution Approach 2:
The patent implements dynamic switching between different source ramp voltage generation circuits based on the required operating period. When high-speed operation is needed, the system dynamically selects the source ramp voltage that maintains waveform stability at shorter periods. This dynamic adaptation allows the system to achieve both high productivity and precise voltage adjustment by optimizing the voltage source selection for each operating condition.
3Device complexity
If analog control circuits are integrated with digital circuits in a single IC, then the device complexity is reduced, but the difficulty of detecting and measuring voltage characteristics increases
Solution Approach 1:
The control circuit acts as an intermediary between the analog source ramp voltage generation circuits and the digital signal processing units. It includes a detection unit that monitors the actual waveform characteristics of the generated ramp voltages and a control unit that processes this information to determine the optimal voltage source selection. This intermediary layer simplifies the integration by providing a standardized interface while handling the complexity of analog-digital interaction.
Solution Approach 2:
The patent implements a feedback mechanism where the control circuit continuously monitors the generated ramp voltage waveform characteristics and uses this information to adjust its selection of source ramp voltages. The detection unit measures actual waveform parameters and feeds this information back to the control unit, which then selects the most appropriate source ramp voltage to maintain optimal performance. This feedback loop simplifies the integrated design by enabling automatic adaptation without requiring complex external measurement equipment.
Data Source
AI summary
An image sensing device includes: a first source ramp voltage generation circuit suitable for generating a first source ramp voltage that is adjusted a first voltage unit for each first period, a second source ramp voltage generation circuit suitable for generating a second source ramp voltage that is adjusted the first voltage unit for each first period and has a set voltage difference from the first source ramp voltage, and a ramp voltage generation circuit suitable for generating a ramp voltage that is adjusted a second voltage unit that is less than the first voltage unit for each second period that is shorter than the first period based on the first and second source ramp voltages and a plurality of first control signals.