Self-scaled Voltage Booster for CMOS Image Sensors
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Solution Overview
Problem
Conventional voltage boosters in CMOS image sensors suffer from excessive ripple in output voltage waveforms due to varying load capacitance, which can impact performance, and existing solutions like linear regulators or ballast capacitance require significant chip area or power, making them unsuitable for common CMOS image sensors.
Innovation Solution
A self-scaled voltage booster system that includes a regulator, a controller, and multiple charge pumps selectively enabled and disabled by the controller based on a duty cycle of the regulator signal, allowing the system to adjust output voltage strength to match load capacitance, thereby reducing ripple without the need for additional area-consuming components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If linear regulator is employed to mitigate ripple in output voltage waveform, then ripple is reduced, but power consumption increases and chip area occupied increases
Solution Approach 1:
The voltage booster is divided into multiple charge pumps (first charge pump, second charge pump, etc.) with different strengths. The controller selectively enables or disables specific charge pumps based on the detected duty cycle of the regulator signal, segmenting the overall boosting function into adjustable components that can be optimized for different operating conditions.
Solution Approach 2:
The system dynamically adjusts the configuration of charge pumps by enabling or disabling specific pumps based on real-time detection of the regulator signal duty cycle. This dynamic reconfiguration allows the voltage booster to adapt its output characteristics to match varying load conditions, optimizing performance while minimizing power consumption and ripple.
2Object-affected harmful factors
If ballast capacitance is added to reduce ripple under lower loading conditions, then ripple is reduced, but chip area occupied increases
Solution Approach 1:
Instead of using a single large ballast capacitance that occupies significant chip area, the invention segments the voltage boosting function into multiple charge pumps with different strengths. This segmentation eliminates the need for large ballast capacitors while still providing effective ripple reduction through selective pump activation.
Solution Approach 2:
The system changes the operational parameters of the voltage booster by selectively enabling or disabling charge pumps based on the duty cycle of the regulator signal. This parameter adjustment allows the system to maintain low ripple under varying load conditions without requiring additional capacitance elements that would increase chip area.
3Object-affected harmful factors
If multiple charge pumps with different strengths are used to match load capacitance, then ripple is reduced and performance is optimized, but device complexity increases
Solution Approach 1:
The controller detects the duty cycle of the regulator signal and uses this feedback information to determine which charge pumps should be enabled or disabled. This feedback mechanism allows the system to automatically adjust its configuration to match load conditions, reducing ripple while maintaining manageable complexity through rule-based control.
Solution Approach 2:
The voltage booster system performs self-adjustment by automatically detecting the regulator signal duty cycle and selectively enabling or disabling charge pumps without external intervention. This self-service capability simplifies the overall control architecture while achieving optimal ripple reduction across different operating conditions.
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
The self-scaled voltage booster effectively mitigates output voltage ripple by dynamically adjusting the strength of charge pumps, maintaining performance across varying load conditions without occupying excessive chip area or power, thus enhancing the efficiency and reliability of CMOS image sensors.
Implementation Method 1
A self-scaled voltage booster includes a regulator, a controller, and two or more charge pumps that can be selectively enabled and disabled by the controller
Data Source
AI summary
Various technologies described herein pertain to automatically adjusting the strength of a voltage booster of an image sensor. A self-scaled voltage booster includes a regulator, a controller, and two or more charge pumps that can be selectively enabled and disabled by the controller. The controller generates controller signals for the charge pumps based on a duty cycle of a regulator signal generated by the regulator. Moreover, the controller can maintain the controller signals without modification for at least a predetermined minimum period of time after a prior modification of at least one of the controller signals. Further, the controller can include a duty cycle and delay module (or a plurality of duty cycle and delay modules) that detects the duty cycle of the regulator signal and maintains the controller signals without modification for at least the predetermined minimum period of time.