Bypass Switch Substrate Voltage Selection for Low-Leakage Regulators
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Solution Overview
Problem
Existing bypass switch implementations in regulators face reliability issues due to high leakage currents and voltage stress, especially when the core supply voltage and regulator output voltage are close and vary independently, making it challenging to select a suitable substrate connection without affecting reliability and leakage.
Innovation Solution
A bulk voltage generation circuit is used to select a voltage for the substrate connection of the bypass switch based on the mode of operation and the presence or arrival sequence of supply voltages, ensuring reliable operation and minimizing leakage by choosing the highest suitable voltage that does not cause reliability issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the substrate of the bypass switch is connected to the I/O supply voltage, then the device can operate in bypass mode, but high cross supply current flows when the core supply voltage is present and the I/O supply has not arrived
Solution Approach 1:
The substrate connection voltage is dynamically selected between I/O supply voltage and core supply voltage based on the arrival sequence of supplies and operational mode. A voltage selection circuit monitors which supply arrived first and automatically connects the substrate to the appropriate voltage rail, enabling bypass mode operation without causing cross supply current.
Solution Approach 2:
A voltage selection circuit acts as an intermediary between the bypass switch substrate and the supply voltages. This intermediary circuit intelligently routes the substrate connection to either I/O supply or core supply based on real-time conditions, preventing direct harmful current flow while maintaining operational capability.
2Reliability
If a thick gate device is used for the bypass switch, then reliability is improved, but the device requires larger area compared to thin gate device
Solution Approach 1:
The invention changes the substrate voltage parameter to match the highest available supply voltage that does not cause reliability issues. This allows the use of thin gate devices with smaller area while maintaining reliability through proper voltage management rather than relying on thick gate geometry.
Data Source
AI summary
Methods and systems for selecting voltage for a substrate connection of a bypass switch include a bulk voltage generation circuit coupled externally to the regulator. The bulk voltage generation circuit is configured to control selection of a voltage from among an Input/Output (I/O) supply voltage and a core supply voltage for a substrate connection of a bypass switch of the regulator. The bulk voltage generation circuit is configured to select the voltage for the substrate connection of the bypass switch based on a mode of operation of the regulator and at least one of a presence or an arrival sequence of the I/O supply voltage and the core supply voltage.