Image Sensor Column Circuit Mode Switching to Cut Noise and Power
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Solution Overview
Problem
Solid-state image pickup apparatuses face challenges in reducing power consumption while minimizing noise interference between different circuit blocks that share a common power supply or ground potential, leading to increased noise during mode switching between high and low power consumption modes.
Innovation Solution
The apparatus includes a semiconductor substrate with pixel columns and column circuits, where each circuit block receives bias voltage via a common wire, with the second circuit block capable of switching between power modes excluding periods when the amplifier circuit in the first block is operating, thereby inhibiting noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the second circuit block switches between first mode and second mode to reduce power consumption, then power consumption is reduced, but noise due to mutual influence on signals may occur in different circuit blocks which receive voltage from a common wire
Solution Approach 1:
The patent applies dynamics by making the operating mode of the second circuit block changeable over time. The circuit block dynamically switches between first mode (with higher power consumption but lower noise) and second mode (with lower power consumption but higher noise) based on the operational state of the amplifier circuit in the first circuit block, thereby optimizing the trade-off between power consumption and noise generation.
Solution Approach 2:
The patent implements periodic action by scheduling the mode switching of the second circuit block to occur at specific periods. The control circuit switches the second circuit block to the first mode during periods when the amplifier circuit is operating, and to the second mode during periods when the amplifier circuit is not operating, creating a periodic pattern of mode transitions that aligns with the operational cycles of the imaging system.
2Device complexity
If different circuit blocks receive power supply voltage from a common wire, then device complexity is reduced, but noise due to mutual influence on signals may occur between circuit blocks
Solution Approach 1:
The patent resolves this contradiction by dynamically controlling the power consumption characteristics of circuit blocks sharing the common wire. By switching the second circuit block between operational modes based on the activity state of other circuit blocks, the system maintains a simple common wire power supply structure while actively managing noise interference through temporal separation of high-noise operations.
Solution Approach 2:
The control circuit acts as an intermediary that coordinates the operation of different circuit blocks sharing the common power wire. It monitors the operational state of the amplifier circuit and accordingly controls the mode of the second circuit block, thereby mediating between the simplicity of shared power supply and the need to prevent noise interference.
Data Source
AI summary
An embodiment of an image pickup apparatus according to the present invention includes, on a semiconductor substrate, an imaging area having a plurality of pixel columns and a plurality of column circuits each of which is provided for each pixel column or a plurality of pixel columns. Each of the column circuits has a first circuit block and a second circuit block, and the first and second circuit blocks receive a bias voltage via a common wire. The first circuit block includes an amplifier circuit. The second circuit block is configured to be capable of switching between a first mode and a second mode with smaller power consumption than the first mode. A shift period from the second mode to the first mode by the second circuit block is a period excluding a period during which an amplifier circuit in the first circuit block is performing an amplifying operation.