Native-Transistor Voltage Level Shifter for Low-Leakage Power-Up
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Solution Overview
Problem
Conventional voltage level shifters in semiconductor devices face challenges in reducing power consumption and leakage current, especially in low power mode, and ensuring reliable powering-up across a wide range of primary power supply voltages, often requiring additional detectors that increase circuit area and degrade DC-DC conversion efficiency.
Innovation Solution
A voltage level shifter design incorporating a complementary pair of transistors and a native transistor in series current conduction paths, with a control module that includes duplicate elements and native transistors to limit leakage current and ensure reliable output voltage, eliminating the need for an isolation signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a detector is added to detect secondary power supply voltage, then the reliability of powering-up is improved, but the circuit area increases and power consumption increases
Solution Approach 1:
The patent combines the voltage detection function with the level shifter circuit itself by using the gate-source voltage of the first transistor as the detection mechanism. This integration eliminates the need for a separate detector circuit, thereby maintaining reliability while reducing circuit area and power consumption.
Solution Approach 2:
The level shifter circuit performs multiple functions: it shifts voltage levels between domains and simultaneously detects the voltage status of the secondary power supply. The first transistor's gate-source voltage serves dual purposes as both a control signal and a voltage detection indicator, enabling the circuit to monitor power supply status without additional components.
2Reliability
If a detector is added to detect secondary power supply voltage, then the reliability of powering-up is improved, but the power consumption increases and DC-DC conversion efficiency degrades
Solution Approach 1:
The voltage detection function is merged into the level shifter circuit using the first transistor's gate-source voltage. This eliminates the need for a separate detector that would consume additional power and degrade DC-DC conversion efficiency, especially in low power mode.
Solution Approach 2:
The level shifter circuit uses its own internal voltage characteristics (gate-source voltage of the first transistor) to detect the secondary power supply status. This self-service approach eliminates the need for external detection circuits that would consume additional power and reduce overall system efficiency.
3Device complexity
If conventional level shifter design is used, then the circuit structure is simple, but the leakage current is high and isolation signal is required
Solution Approach 1:
The patent changes the operating parameters of the transistors by introducing native transistors with different threshold voltage characteristics. The native transistors are configured to limit leakage current through their inherent electrical characteristics, reducing harmful leakage without requiring complex isolation circuits or signals.
4Device complexity
If conventional level shifter design is used, then the circuit structure is simple, but the output voltage control is unreliable with wide primary power supply voltage range
Solution Approach 1:
The patent introduces native transistors with specific threshold voltage parameters that remain stable across wide primary power supply voltage ranges. These transistors are configured in the level shifter circuit to provide reliable output voltage control regardless of variations in the primary power supply voltage, maintaining reliability without significantly increasing circuit complexity.
Data Source
AI summary
A level shifter in a primary voltage domain has a control module receiving an input signal from a secondary voltage domain for controlling operation of the level shifter. The control module includes a complementary pair of transistors and a first native transistor connected in a series current conduction path in the primary voltage domain. The complementary pair of transistors have gates connected to receive the input signal and the first native transistor has a gate connected to limit to a leakage current the current in the series current conduction path.