Floating Level Translator With Adaptive Bypass for Low-Voltage Headroom
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Solution Overview
Problem
Floating high-voltage level translators face limitations in supply voltage range, propagation speed, and common mode transient immunity (CMTI) at low voltages due to loss of headroom, which makes them susceptible to noise and errors.
Innovation Solution
The implementation of an adaptive bypass circuit that selectively engages during low-voltage operation to bypass high-voltage protection elements, increasing headroom swing without compromising propagation speed, quiescent current, or CMTI, and allowing high-voltage protection elements to be optimally sized for propagation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-voltage protection elements are used in floating high-voltage level translators, then reliability is improved, but headroom is reduced at low voltages causing loss of functionality
Solution Approach 1:
The bypass circuit is configured to dynamically engage during low-voltage operation and disengage during high-voltage operation. This dynamic switching allows the level translator to adapt its protection mechanism based on operating conditions, maintaining both low-voltage functionality and high-voltage protection capability without permanent headroom loss.
Solution Approach 2:
The harmful effect of the bypass circuit on headroom is extracted and isolated to only affect high-voltage operation. By placing the bypass circuit in parallel with the high-voltage protection elements and controlling it to disengage during high-voltage operation, the protection elements can be optimally sized for propagation speed without being constrained by low-voltage headroom requirements.
2Speed
If high-voltage protection elements are sized for optimal propagation speed, then speed is improved, but low-voltage headroom is insufficient causing operation failures
Solution Approach 1:
The bypass circuit acts as an intermediary that compensates for the headroom deficiency of optimally-sized high-voltage protection elements during low-voltage operation. By providing an additional conduction path in parallel, the bypass circuit enables the protection elements to be sized for speed optimization while maintaining sufficient headroom for low-voltage functionality.
3Adaptability or versatility
If bypass circuit is always engaged to improve low-voltage headroom, then low-voltage operation is enhanced, but propagation speed decreases due to additional current paths
Solution Approach 1:
The bypass circuit is dynamically controlled to engage only during low-voltage operation and disengage during high-voltage operation. This dynamic behavior allows the system to optimize for low-voltage headroom when needed while maintaining optimal propagation speed during high-voltage operation by removing the additional current path.
4Adaptability or versatility
If bypass circuit is added to enhance low-voltage capability, then adaptability is improved, but device complexity increases
Solution Approach 1:
The bypass circuit is designed to serve multiple functions: it provides headroom enhancement during low-voltage operation, protects against negative voltage transients, and can be implemented using standard FET devices already present in the level translator. This multi-functionality reduces the need for additional dedicated components, thereby limiting the increase in device complexity.
Data Source
AI summary
Techniques are described herein to enhance capability of floating level translators. For example, increased headroom is accomplished by adaptively bypassing the protection elements of the voltage level translator. In an example, a floating level translator can translate an input signal from a low-voltage domain to a high-voltage domain. A bypass circuit is coupled across the protection elements. The bypass circuit selectively engages during low-voltage operation (e.g., thereby providing a lower loss path relative to loss caused by the high-voltage protection elements and thus increasing the headroom swing), and disengages responsive to the high-voltage reference rail of the high-voltage domain exceeding a threshold or otherwise being high enough (e.g., greater than the potential of the low-voltage domain power rail). The bypass circuit can be implemented in a relatively low-complexity manner (e.g., back-to-back high-voltage FETs) without additional signals to control low-voltage capability.