Level Shifter Circuit for Power-Up Order and Withstand Voltage Control
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Solution Overview
Problem
Existing semiconductor integrated circuit devices face issues with withstand voltage violations and unnecessary current flow when a high-voltage power source rises before a low-voltage power source, leading to potential transistor damage and inefficiencies.
Innovation Solution
A semiconductor integrated circuit device configuration that includes p-type transistors, a step-down circuit, a power source switch circuit, and level shifter circuits, where the gate of the first transistor is connected to the output of a level shifter circuit and the gate of the second transistor is connected to a higher power source, ensuring no withstand voltage violation occurs regardless of the power source rising order.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a high-voltage power source rises before a low-voltage power source, then the circuit can operate with high-voltage signal input, but withstand voltage violations occur in transistors causing potential damage
Solution Approach 1:
A level shifter circuit is introduced as an intermediary between the high-voltage power source and the gate of the first transistor. This level shifter converts the high-voltage signal to a low-voltage signal, ensuring that the gate voltage of the first transistor never exceeds the low-voltage power source level, even when the high-voltage power source rises first. This mediator prevents direct high-voltage stress on the transistor while allowing high-voltage operation.
2Adaptability or versatility
If a high-voltage power source rises before a low-voltage power source, then high-voltage signal processing is enabled, but unnecessary current flows from the high-voltage power source through the low-voltage power source to ground
Solution Approach 1:
The level shifter circuit performs preliminary voltage conversion before the main transistor switches. By converting the high-voltage power source signal to low-voltage at the gate control stage beforehand, the circuit ensures that the first transistor only switches when properly controlled, preventing premature switching that would cause unnecessary current flow through the low-voltage power source to ground.
Data Source
AI summary
A semiconductor integrated circuit device includes: first and second transistors provided between a first power source and an output terminal; a step-down circuit that generates a second power source from the first power source; a power source switch circuit that outputs, as a fourth power source, a higher one of potentials of the second power source and a third power source; and a level shifter circuit that transits between the first power source and a fourth power source. The first transistor has a gate connected to an output of the level shifter circuit; the second transistor has a gate connected to the fourth power source.