Level Shift Circuit Isolation for Low-Voltage Startup Stability
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Solution Overview
Problem
In semiconductor devices, level shift circuits experience instability and malfunction when the low power source voltage is not sufficiently supplied, leading to issues with signal handover from the low voltage side core power source to the high voltage side I/O power source.
Innovation Solution
A semiconductor device configuration that includes specific transistors and inverters operating at different power source voltages, with additional transistors connected in parallel to isolate nodes and maintain stable voltage levels, ensuring the level shift circuit functions correctly even when the low power source voltage is insufficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a level shift circuit is employed for signal handover from low voltage side to high voltage side, then signal level shifting is achieved, but the output signal becomes unstable when the low power source voltage is not sufficiently supplied
Solution Approach 1:
The isolation transistors are activated in advance when voltage instability is detected, preventing the unstable low voltage from affecting the level shift circuit before damage occurs. This preliminary protective action ensures signal stability without requiring complex recovery mechanisms.
Solution Approach 2:
Isolation transistors are introduced as intermediary components between the low voltage side and the level shift circuit. These transistors act as mediators that can disconnect the unstable low voltage source from the sensitive level shift circuit, preventing signal instability while maintaining circuit functionality.
2Reliability
If additional protection circuits are added to prevent malfunction during low voltage conditions, then reliability is improved, but device complexity increases
Solution Approach 1:
The isolation transistors are controlled by voltage detection circuits that automatically detect low voltage conditions and activate protection without external intervention. This self-service mechanism prevents malfunction during low voltage conditions while avoiding the need for complex external control systems or additional protection circuits.
Data Source
AI summary
A semiconductor device, includes: a first first-conductivity-type transistor supplied with a first power source voltage and controlled by an output signal of a first input inverter; a second first-conductivity-type transistor supplied with the first power source voltage and controlled by an output signal of a second input inverter that inverts an output signal of the first input inverter; a first and a second second-conductivity-type transistor supplied with a second power source voltage; and a third and a fourth first-conductivity-type transistor that are connected in parallel either between the first first-conductivity-type transistor and the first second-conductivity-type transistor or between the second first-conductivity-type transistor and the second second-conductivity-type transistor, and that are configured to isolate either a first node connected to the first first-conductivity-type transistor or a second node connected to the second first-conductivity-type transistor from the second power source voltage in accordance with the first power source voltage.