Reference Voltage Generator Grounding to Prevent Floating Voltages
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Solution Overview
Problem
Electronic devices experience floating voltages due to incomplete power sequencing, which can affect operations after power cycling, particularly when general purpose input/output (GPIO) pins receive less than the specified power supply voltage during device power on or off.
Innovation Solution
A circuit structure incorporating a pass gate with transistors coupled to an input signal and an inverter with a back-gate terminal coupled to ground, which grounds the reference voltage generator output when the supply voltage is below a target level, preventing floating voltages by ensuring power sequencing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the reference voltage generator remains active during power down, then the voltage reference is available for quick power on, but floating voltages occur affecting device operations
Solution Approach 1:
The patent applies preliminary action by proactively grounding the reference voltage generator output when power supply voltage drops below a threshold level, before complete power down occurs. This preventive grounding action eliminates floating voltages that would otherwise persist after power off, ensuring reliable device operations during subsequent power cycles while maintaining the ability to quickly power on by simply restoring the voltage supply.
2Reliability
If complex voltage detection schemes are used to prevent floating voltages, then device operation reliability improves, but circuit complexity increases
Solution Approach 1:
The patent implements self-service by designing a circuit where the reference voltage generator's own output voltage serves as the detection signal. When this voltage drops below a predetermined threshold, it automatically triggers the grounding action through the existing inverter and transistor circuitry. This self-detecting, self-actuating mechanism prevents floating voltages and ensures reliable operation without requiring external voltage detection schemes or additional control circuits, thereby maintaining simplicity.
Data Source
AI summary
Embodiments of the disclosure provide a structure and method to ground a reference voltage generator based on a detected supply voltage. A circuit structure according to the disclosure includes a pass gate. The pass gate includes a pair of transistors each coupled to an input signal. One of the pair of transistors of the pass gate includes a gate coupled to a static reference voltage. An inverter couples an output from the pass gate to a device node. The inverter includes a drain terminal, a gate terminal, and a back-gate terminal coupled to ground.