Negative Voltage Charge Pump Regulation for Gate Oxide Protection
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Solution Overview
Problem
Existing electronic circuits face challenges in generating negative voltages due to the susceptibility of gate oxides to over-stress, limiting the ability to change logic states after the low logic voltage level has been lowered.
Innovation Solution
A circuit design that includes a negative voltage generation circuit with a charge pump, comparator, and bypass transistors, allowing for the regulation of intermediate and final negative voltage levels without requiring a separate negative voltage source, enabling logic circuitry to change states at an intermediate negative voltage level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a negative voltage generation circuit is used, then negative voltages can be generated for electronic circuits, but the gate oxide of devices used to generate the negative voltages becomes susceptible to being over stressed
Solution Approach 1:
The patent applies preliminary action by asserting a protection mode signal before the negative voltage reaches levels that would cause over-stress. The protection mode signal is asserted when the negative voltage exceeds a threshold (e.g., -3.3V), proactively preventing damage before it occurs. This allows the circuit to operate safely by preparing protective measures in advance rather than reacting after damage occurs.
Solution Approach 2:
The protection mode signal acts as an intermediary between the negative voltage generation circuit and the logic circuitry. When asserted, it mediates the interaction by forcing the logic circuitry into a high-impedance state, preventing direct exposure to harmful voltage levels while still allowing the negative voltage to be generated and used when safe.
2Ease of operation
If the low logic voltage level is lowered to a negative value, then negative voltage operation is achieved, but the logic circuitry cannot change logic states
Solution Approach 1:
The patent applies dynamics by making the protection mode signal dynamic rather than static. The protection mode signal transitions between asserted and unasserted states based on the negative voltage level. When the negative voltage is within safe operating ranges, the protection mode is unasserted, allowing logic circuitry to change states freely. When the voltage exceeds thresholds, the protection mode asserts to prevent state changes, thus dynamically adapting the circuit's operational characteristics to current conditions.
3Adaptability or versatility
If additional negative voltage sources are used, then regulation at different negative voltage levels is possible, but device complexity increases
Solution Approach 1:
The patent applies universality by designing a single negative voltage generation circuit that can operate at multiple voltage levels (-3.3V, -5V, -12V) through a unified charge pump architecture. The same circuit infrastructure supports different operating modes by adjusting control signals and protection mode assertions, eliminating the need for separate dedicated circuits for each voltage level while maintaining full functionality at all levels.
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
Enables the generation of regulated negative voltage levels, protecting transistors from damage and allowing logic circuitry to operate and change states effectively, without the need for additional negative voltage sources, thus enhancing the reliability and efficiency of negative voltage generation in electronic circuits.
Implementation Method 1
negative voltage generation circuit with a charge pump, comparator, and bypass transistors, allowing for the regulation of intermediate and final negative voltage levels
Data Source
AI summary
A first logic state is at a first output voltage level at a first output of a level shifter that selects a first negative regulation voltage level in response to the first logic state. A negative supply voltage begins at first potential and decreases to the first negative regulation voltage level. The first output voltage level decreases as the negative supply voltage decreases. The first output of the level shifter is switched from the first logic state to a second logic state in response to the negative supply voltage reaching the first negative regulation voltage level. The second logic state is provided at a second output voltage level that selects a second negative regulation voltage level for the negative regulation voltage. The first output of the level shifter remains at the second logic state but is reduced in voltage.