Dual-Path Level Shifter for MOSFET Voltage Stress Control
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Solution Overview
Problem
Existing level shifter circuits face challenges in efficiently shifting input signal levels without causing voltage stress on MOSFET devices, particularly in ensuring that junctions of these devices experience voltage levels within safe thresholds.
Innovation Solution
A dual path level shifter circuit is implemented, utilizing a combination of voltage-to-current and current-to-voltage converters, along with MOSFET devices configured to route input signals through alternative paths based on control signals, thereby preventing voltage stress by limiting junction voltages to below a stress threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional level shifter circuit is used to shift input signal levels, then the signal level shifting function is achieved, but voltage stress exceeds the stress threshold level at junctions of MOSFET devices
Solution Approach 1:
The level shifter circuit is divided into two separate signal paths: a first signal path for routing signals without level shifting, and a second signal path for routing signals with level shifting. This segmentation allows the circuit to avoid voltage stress by selecting the appropriate path, thereby preventing MOSFET junctions from experiencing excessive voltage while maintaining the level shifting function.
Solution Approach 2:
The circuit dynamically switches between two operating conditions by controlling which signal path is active. A control mechanism selects the first signal path when voltage stress would exceed thresholds, and switches to the second signal path when level shifting is required and safe to perform. This dynamic adaptation ensures MOSFET reliability while maintaining signal level shifting capability.
2Device complexity
If the input signal is routed through a single path for level shifting, then the level shifting function is simplified, but voltage stress on MOSFET junctions cannot be controlled within safe thresholds
Solution Approach 1:
The circuit is segmented into two distinct signal paths with different functions: the first path maintains simple signal routing without level shifting, while the second path performs level shifting when conditions permit. This segmentation resolves the contradiction by providing structural complexity that enables reliability control through path selection.
Solution Approach 2:
A control mechanism acts as an intermediary that monitors voltage levels and selectively activates the appropriate signal path. This intermediary ensures that level shifting operations only occur when MOSFET junction voltages remain within safe thresholds, thereby maintaining reliability while managing the complexity introduced by dual paths.
3Reliability
If voltage-to-current and current-to-voltage converters are used for level shifting, then the input signal level is successfully shifted to output signal level, but the circuit complexity increases
Solution Approach 1:
The voltage-to-current converters and current-to-voltage converters are designed to serve multiple functions: they enable level shifting when needed while also allowing direct signal passage when level shifting is not required. This multi-functionality justifies the added complexity by providing accurate and reliable level shifting capability when voltage stress conditions permit.
Solution Approach 2:
The complex converter circuits are localized to specific regions of the circuit where level shifting is actually needed, rather than being universally applied to all signal paths. This allows the circuit to maintain simplicity in the direct routing path while concentrating the complexity only where it provides value for accurate level shifting.
Data Source
AI summary
Dual path level shifter methods and devices are described. The described level shifter devices can comprise voltage-to-current and current-to-voltage converters.