High-Speed Level Shifter Circuit for Asynchronous Power-Up Leakage
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Solution Overview
Problem
High-speed voltage level shifter circuits suffer from significant leakage current due to asynchronous power-up sequencing, which leads to the formation of forward biased PN-junction diodes, causing performance degradation.
Innovation Solution
Incorporating a pair of series connected switches, such as pass gate transistors, between the input terminal and the voltage adjusting circuit, where each switch is controlled by a different supply voltage, ensuring that both power supplies are powered up before a signal is passed through, preventing forward biasing of PN-junction diodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-speed voltage level shifter circuits are used for signal conversion between different voltage domains, then signal conversion speed is improved, but leakage current increases due to forward biased PN-junction diodes during asynchronous power-up sequencing
Solution Approach 1:
The circuit performs preliminary power-up sequencing checks before enabling signal conversion. The first power supply must be fully powered up before the second power supply is enabled, ensuring that PN-junction diodes are not forward biased during transition. This preliminary action prevents leakage current while maintaining high-speed operation capability.
Solution Approach 2:
The circuit dynamically controls the enabling of power supplies based on their power-up status. Switches are used to dynamically connect or disconnect power supply domains, ensuring that signal conversion paths are only activated when both power supplies are properly powered up, thereby preventing forward biasing of PN-junction diodes.
2Adaptability or versatility
If asynchronous power-up sequencing is allowed in voltage level shifter circuits, then power supply flexibility is improved, but forward biased PN-junction diodes are created causing performance degradation
Solution Approach 1:
The circuit checks the power-up status of both power supplies before enabling signal conversion. This preliminary verification ensures that the first power supply is fully powered up before the second power supply is activated, preventing forward biased PN-junction diodes while still allowing flexible power-up sequences.
Solution Approach 2:
Switches act as intermediaries between the power supplies and the voltage level shifter circuit. These switches control the connection based on power-up status, mediating between the flexible power supply sequencing requirement and the need to prevent forward biased PN-junction diodes for reliable operation.
3Loss of energy
If switches are added to control power supply sequencing in voltage level shifter circuits, then leakage current is reduced by preventing forward biased PN-junction diodes, but device complexity increases
Solution Approach 1:
The switches are configured to automatically enforce proper power-up sequencing based on the power supply status. This preliminary control mechanism prevents forward biased PN-junction diodes and reduces leakage current without requiring complex external control logic, as the sequencing is inherently managed by the circuit structure.
Solution Approach 2:
The voltage level shifter circuit itself provides the control function for power-up sequencing through its internal switches and power supply status detection. The circuit serves itself by automatically preventing forward biased PN-junction diodes based on the power supply states, eliminating the need for separate complex control circuits.
Data Source
AI summary
Disclosed are embodiments of a design structure for a voltage level shifter circuit that operates without forward biasing junction diodes, regardless of the sequence in which different power supplies are powered up. The circuit embodiments incorporate a pair of series connected switches (e.g., transistors) between an input terminal and a voltage adjusting circuit. Each switch is controlled by a different supply voltage from a different power supply. Only when both power supplies are powered-up and the different supply voltages are received at both switches will a first signal generated using one of the supply voltages be passed to a voltage adjusting circuit and thereafter converted into a second signal representative of the first signal, but generated using the second supply voltage. Incorporation of the pair of series connected switches into the voltage level shifter circuit prevents forward biasing of junction diodes in the circuit and thereby prevents current leakage from the power supplies.