Intrinsic Comparator Delay for Output Clamping Circuit Ripple Mitigation
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Solution Overview
Problem
Conventional overvoltage protection circuits in mobile devices suffer from undesirable ripple voltage due to multiple reference voltages, which can damage electronic components and reduce stability under temperature and load changes.
Innovation Solution
A protection circuit employing a comparator with a single reference input and an intrinsic delay circuit, utilizing a first and second switch with feedback paths to mitigate output ripple, ensuring stable switching operations and reduced circuit complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple reference voltages are employed to provide hysteresis, then the response of the clamping circuit can be tailored, but an undesirable amount of ripple voltage is generated at the output
Solution Approach 1:
The patent extracts the hysteresis function from the reference voltage inputs and relocates it to the output feedback path. By using a single reference voltage and adding hysteresis through output feedback, the harmful ripple voltage generated by multiple reference voltages is eliminated while preserving the beneficial tailoring of clamping circuit response.
Solution Approach 2:
The patent introduces an intermediary element (resistor) in the feedback path that mediates between the output voltage and the reference voltage input. This intermediary enables hysteresis to be achieved through output feedback rather than through multiple reference voltages, thereby reducing output ripple voltage while maintaining adaptability.
2Adaptability or versatility
If multiple reference voltages are used to provide hysteresis, then the clamping circuit response can be tailored, but circuit complexity increases
Solution Approach 1:
The patent extracts the hysteresis functionality from the reference voltage generation stage and relocates it to the output feedback stage. This eliminates the need for multiple reference voltage inputs and their associated circuitry, thereby reducing circuit complexity while maintaining the ability to tailor the clamping circuit response.
Solution Approach 2:
The patent makes the single reference voltage input serve multiple functions: it provides the threshold voltage for clamping and, through the feedback path, provides hysteresis. This multi-functionality eliminates the need for separate reference voltage circuits for each function, thereby reducing overall circuit complexity.
3Reliability
If conventional overvoltage protection circuits are used, then overvoltage conditions can be detected, but stability under temperature and load changes is reduced
Solution Approach 1:
The patent implements feedback from the output voltage to the reference voltage input through a resistor in the non-inverting input path. This feedback mechanism automatically adjusts the effective threshold voltage based on output conditions, compensating for temperature and load variations and thereby improving stability while maintaining overvoltage detection capability.
Data Source
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AI summary
A circuit includes a comparator to generate a clamp output signal by monitoring an output voltage and a reference voltage that sets a clamp voltage threshold for the output voltage. The clamp output signal is employed to limit an input voltage from exceeding the clamp voltage threshold. A first switch supplies the reference voltage to the comparator. The first switch forms a portion of an intrinsic delay circuit with a first feedback path in the comparator to mitigate ripple in the output voltage. A second switch is coupled to the input voltage and a second feedback path in the comparator. The second switch forms another portion of the intrinsic delay circuit with the first switch, the first feedback path, and the second feedback path in the comparator to further mitigate ripple in the output voltage.