Image Sensor Row ADC Gain Switching for Fast Low-Power Readout
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Solution Overview
Problem
Existing image pickup apparatuses face challenges in achieving fast readout speeds while maintaining low power consumption, as increasing clock frequency to enhance AD conversion speed leads to increased power consumption.
Innovation Solution
The image pickup apparatus includes a controller that adjusts the AD conversion gain based on the output level of the readout circuit, using a row ADC that adjusts AD conversion gain depending on predetermined conditions, allowing for variable bit resolutions and efficient power management by changing the gain of the AMP based on incident light intensity, frame rate, temperature, and operation mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If clock frequency is increased to speed up AD conversion, then readout speed is improved, but power consumption increases
Solution Approach 1:
The patent applies dynamics by making the AD converter's operating mode adjustable rather than fixed. The system can switch between high-speed mode (for low light conditions requiring fast readout) and low-power mode (for high light conditions where slower readout is acceptable). This dynamic adaptation resolves the contradiction by allowing the system to optimize for speed when needed and for power efficiency when possible.
Solution Approach 2:
The patent changes the operating parameters of the AD converter based on incident light intensity. When light intensity is low, the system increases clock frequency to maintain fast conversion speed. When light intensity is high, the system decreases clock frequency to reduce power consumption. This parameter adaptation allows the system to balance speed and power consumption based on actual operating conditions.
2Measurement precision
If AD conversion gain is adjusted to optimize bit resolution, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system performs self-service by automatically adjusting AD conversion gain based on incident light intensity without requiring complex external control. The controller monitors light conditions and autonomously selects appropriate gain settings and bit resolution levels, simplifying the overall control architecture while maintaining optimal measurement precision.
Solution Approach 2:
The patent adjusts AD conversion gain parameters dynamically based on incident light intensity. The system switches between different gain levels and bit resolution configurations (e.g., 10-bit mode for low light, 8-bit mode for high light) to optimize measurement precision while managing complexity through predefined operational modes.
Data Source
AI summary
An image pickup apparatus includes a plurality of pixels, a readout circuit configured to read out pixel signals from the pixels for each pixel row, an analog to digital (AD) converter configured to adjust an AD conversion gain depending on an output level of the readout circuit and to provide a signal from the readout circuit with an AD conversion to output image data, and a controller configured to control the AD conversion gain of the AD converter depending on a predetermined condition.