Imager Readout Chain Power Management via Switch Circuit
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Solution Overview
Problem
Current CMOS imagers with multiple readout chains consume high power, especially as the demand for higher resolution increases, which is a concern in applications with limited power supply, such as mobile devices.
Innovation Solution
The imager selectively enables or disables readout chains and directs signals to only the enabled chains for processing, reducing power consumption by using a single readout chain in low power modes and combining this with selective pixel signal readout and processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple readout chains are used to increase imaging speed and resolution, then productivity is improved, but power consumption increases
Solution Approach 1:
The patent implements dynamic configuration of readout chains by introducing a configuration register that allows the number of active readout chains to be adjusted based on operating conditions. The system can switch between single-chain and multi-chain modes, enabling adaptive power management while maintaining imaging capability. This dynamic reconfiguration resolves the contradiction by allowing the system to use multiple chains only when high-speed imaging is required, rather than maintaining multiple chains in a static high-power state.
2Speed
If multiple readout chains are enabled simultaneously, then imaging speed increases, but power consumption increases
Solution Approach 1:
The patent employs periodic switching between single-chain and multi-chain operating modes based on imaging requirements. The configuration register enables the system to alternate between power-saving single-chain mode during normal operation and high-speed multi-chain mode when rapid imaging is needed, resolving the speed-power contradiction through time-multiplexed operation rather than continuous high-power consumption.
3Reliability
If all readout chains are always active, then reliability is improved, but power consumption increases
Solution Approach 1:
The patent changes the operational parameter of readout chain quantity from a fixed state to a variable state controlled by a configuration register. By allowing the number of active chains to be adjusted between 1 and N based on requirements, the system maintains reliability when multiple chains are needed while reducing power consumption when single-chain operation suffices, resolving the reliability-power contradiction through parameter variability.
Data Source
AI summary
An imager with a switch circuit located between, and connected to, the pixel array and associated readout chains. In one embodiment the switch is located within the column sample and hold circuitry; in another embodiment the switch is located between the column sample and hold circuitry and the readout chains. The switch circuit ensures that signals from the column sample and hold circuitry are directed to enabled readout chains, which allows selective enabling/disabling of readout chains. By disabling readout chains, the imager's power consumption is reduced.