Power-On Reset Circuit Using Independent Current Sensing
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Solution Overview
Problem
Existing power-on reset circuits that employ positive feedback suffer from trapped charge issues, leading to unreliable operation at low supply voltage levels and limited scalability, making them less reliable and portable across different technologies and voltage ranges.
Innovation Solution
A power-on reset circuit design that eliminates positive feedback by using independent and dependent current circuits to determine the supply voltage state, ensuring the current used is independent of the supply voltage level, thereby eliminating charge trapping and allowing for scalable and portable operation across various technologies and voltage ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If positive feedback is employed in power-on reset circuits, then the triggering voltage can be set high enough for the application, but trapped charge among the diodes prevents complete turn-off of other components, reducing reliability
Solution Approach 1:
The patent removes the positive feedback mechanism from the power-on reset circuit, extracting the harmful trapped charge effect. By eliminating the regenerative feedback loop that causes charge to be trapped in diode junctions, the circuit avoids the reliability issues associated with incomplete component turn-off while maintaining the voltage threshold functionality through alternative means.
2Reliability
If multiple stacked diodes are used to set triggering voltage, then the voltage threshold is sufficient for the application, but the circuit becomes less reliable and portable across different technologies and voltage ranges
Solution Approach 1:
The patent changes the fundamental parameters of the power-on reset circuit by replacing the multi-diode stacked configuration with a single-diode design combined with a transistor-based voltage threshold mechanism. This parameter change reduces the number of components and eliminates the trapped charge issue while maintaining the necessary voltage threshold functionality, thereby improving portability across different technologies and voltage ranges.
3Reliability
If positive feedback circuits are used, then voltage threshold can be achieved, but operation at low supply voltage levels becomes unreliable
Solution Approach 1:
The patent introduces a transistor as an intermediary element that mediates between the supply voltage and the reset trigger mechanism. The transistor's base-emitter junction serves as a voltage threshold element that does not suffer from trapped charge effects, allowing reliable operation at low supply voltage levels. This intermediary approach enables the circuit to function reliably across a wider voltage range without the limitations of diode-based positive feedback circuits.
Data Source
AI summary
Apparatus, systems, and methods may include providing a power-on reset function to many types of receiving circuitry, including radio frequency identification (RFID) tag processing circuitry. Thus, the power-on reset function may be realized by applying a supply voltage to a power-on reset circuit coupled to RFID tag processing circuitry. Operations may include sensing a first current substantially independent of the supply voltage, sensing a second current substantially dependent on the supply voltage, and indicating a power-on reset condition based on a comparison between the first current and the second current. Additional apparatus, systems, and methods are disclosed.