Dual-Stage Level Shifter Circuit for Unstable Supply Voltages
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Solution Overview
Problem
Existing level shifter circuits for semiconductor integrated circuits face issues with unstable power supply voltages, leading to erroneous signal transmission and operational failures due to lack of margin in low voltage power supply control and separate operation of input and output sides.
Innovation Solution
A level shifter circuit is designed with two voltage conversion circuits and an output latch circuit, utilizing transistors with different threshold voltages to generate and manage complementary signals across multiple power supply voltages, ensuring stable operation even when power supply voltage is unstable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a level shifter circuit is used to convert signal levels between different power supply voltages, then signal level conversion is achieved, but erroneous signal transmission occurs when power supply voltage fluctuates
Solution Approach 1:
The patent applies preliminary action by enabling the output side circuit before the input side circuit during power-on. This ensures that when power is supplied, the output side is already active and ready to receive signals, preventing erroneous signal transmission that would occur if the input side were activated first. The power supply voltage fluctuation detection mechanism also acts in advance to control the timing of circuit activation.
Solution Approach 2:
The patent implements feedback by using the power supply voltage fluctuation detection signal to control the activation timing of both input and output sides. The detection mechanism continuously monitors voltage stability and uses this feedback information to determine when it is safe to activate the level shifter circuit, thereby preventing operation during unstable voltage conditions.
2Reliability
If separate control of input and output sides is implemented, then power supply sequencing is achieved, but additional control mechanisms are required
Solution Approach 1:
The patent applies self-service by using the power supply voltage fluctuation detection mechanism to automatically control the activation timing of both input and output sides. The detection circuit monitors voltage stability and autonomously determines when to enable each side, eliminating the need for external control signals or additional control logic that would otherwise be required to sequence the power supply activation.
3Use of energy by moving object
If low voltage power supply is used to control transistors, then power consumption is reduced, but insufficient margin causes erroneous operation
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the power supply voltage based on operational requirements. During normal operation, low voltage is used to minimize power consumption. However, during power-on or voltage transition periods, the voltage is temporarily increased to provide sufficient margin for reliable transistor operation. This dynamic voltage adjustment resolves the contradiction between low power consumption and adequate operating margin.
Data Source
AI summary
A level shifter circuit that properly operates even when the power supply voltage is unstable. A level shifter circuit includes a first level shifter unit, a second level shifter unit, and a latch unit. In the first level shifter unit, a transistor is connected to a power supply line to generate drive voltage that is lower than a first power supply voltage. The first level shifter unit outputs complementary signals from the drive voltage. The output of the first level shifter unit is provided to the second level shifter unit. The second level shifter unit converts a complementary signal to a signal having a second power supply voltage. Based on this signal, a signal of the latch unit is switched.