Pre-Charge Level Shifter Without Cross-Coupled Switches
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Solution Overview
Problem
Existing level shifters for transferring digital data between different voltage domains face challenges in minimizing energy consumption, especially in wide data buses, and often require cross-coupled transistors and additional gating information, which increases energy consumption and layout area.
Innovation Solution
A level shifter design that includes a pre-charge circuit and a keeper circuit, eliminating the need for cross-coupled switches and separate discharging branches, with a method that controls the first and second control switches using supply voltages to maintain logical values without requiring gating information from another level shifter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cross-coupled transistors and separate discharging branches are used in level shifters, then the reliability of voltage level transfer is improved, but the energy consumption and layout area increase
Solution Approach 1:
The patent extracts and removes the cross-coupled transistor structure and separate discharging branches from the level shifter design. By eliminating these components, the invention reduces energy consumption and layout area while maintaining the essential voltage level transfer functionality through a simplified single discharging path architecture.
Solution Approach 2:
The patent merges the pre-charging function and discharging function into a single integrated circuit path. Instead of having separate pre-charging branches and discharging branches, the invention combines these functions so that the same circuit path serves both purposes, thereby reducing the overall component count and energy consumption.
2Reliability
If cross-coupled transistors are used in level shifters, then the voltage level transfer reliability is improved, but the layout area increases
Solution Approach 1:
The patent extracts and removes the cross-coupled transistor structure and separate discharging branches from the level shifter design. By eliminating these components, the invention reduces energy consumption and layout area while maintaining the essential voltage level transfer functionality through a simplified single discharging path architecture.
3Measurement precision
If additional gating information from another level shifter is used, then the control precision is improved, but the device complexity and energy consumption increase
Solution Approach 1:
The patent implements self-service control where the level shifter uses its own output signal to control its own operation through the keeper circuit. The keeper circuit monitors the output voltage level and automatically adjusts the pre-charging switch accordingly, eliminating the need for external gating information from other level shifters and reducing overall system complexity.
Data Source
AI summary
A level shifter comprises a first control switch (207) for connecting an output terminal to a first supply voltage (VDDH) to set an output signal to be high, and a second control switch (208) for connecting the output terminal to a signal ground (GND) to set the output signal to be low. The level shifter comprises a pre-charging switch (210) for connecting the output terminal to the first supply voltage, and an input gate circuit (211) for controlling an ability of an input signal to control the second control switch. The level shifter comprises a keeper circuit (212) for controlling the first control switch based on the output signal. The first control switch is controlled with the first supply voltage when the output signal is low, and with a second supply voltage that is between the first supply voltage and the signal ground when the output signal is high.