Floating High-Voltage Level Translator With Adaptive Protection Bypass
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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 performance
Solution Approach 1:
The bypass circuit dynamically switches between enabled and disabled states based on voltage conditions. During low-voltage operation, the bypass circuit is enabled to provide additional headroom by bypassing the protection elements. During high-voltage operation, the bypass circuit is automatically disabled to allow the protection elements to function. This dynamic switching resolves the contradiction by adapting the circuit configuration to operational conditions.
Solution Approach 2:
The bypass circuit acts as an intermediary element that can be inserted between the signal path and the protection elements. It provides an alternative conduction path that bypasses the protection elements when needed, effectively mediating between the conflicting requirements of protection and headroom without requiring fundamental changes to the protection architecture.
2Reliability
If protection elements are sized for high-voltage protection, then reliability is improved, but propagation speed deteriorates due to increased capacitance
Solution Approach 1:
The bypass circuit dynamically alters the effective capacitance seen by the signal path. When enabled during low-voltage operation, it provides a low-impedance path that bypasses the capacitive protection elements, effectively reducing their impact on propagation speed. When disabled during high-voltage operation, the protection elements remain in the signal path to provide protection. This dynamic behavior resolves the speed-protection contradiction.
Solution Approach 2:
The bypass circuit effectively extracts or removes the protection elements from the critical signal path during low-voltage operation where they would otherwise degrade propagation speed. By providing an alternative path around these elements when not needed for protection, the circuit separates the protection function from the high-speed signal path during critical operation modes.
3Ease of operation
If bypass circuit is enabled during low-voltage operation, then headroom swing is increased, but circuit complexity increases
Solution Approach 1:
The bypass circuit is designed to automatically enable and disable based on voltage conditions detected within the circuit itself, without requiring external control signals or complex management logic. The circuit self-regulates its configuration based on operational parameters, providing the headroom enhancement function while minimizing the complexity of control mechanisms.
Solution Approach 2:
The bypass circuit functionality is integrated into the existing level translator architecture, sharing common components and signal paths where possible. The bypass transistors are positioned to work with the existing protection element structure, merging the headroom enhancement function with the protection function rather than adding completely separate circuitry.
4Adaptability or versatility
If bypass circuit is added to enhance low-voltage performance, then adaptability is improved, but power dissipation may increase
Solution Approach 1:
The bypass circuit operates dynamically, being enabled only during low-voltage operation modes where it is needed to provide adequate headroom. During normal high-voltage operation, the bypass circuit is disabled to eliminate its power consumption. This conditional operation ensures that the adaptability benefit is achieved while minimizing continuous power dissipation overhead.
Solution Approach 2:
The bypass circuit engages and disengages periodically based on the operational mode transitions between low-voltage and high-voltage operation. This periodic activation pattern allows the circuit to provide enhanced low-voltage performance when needed while remaining inactive during high-voltage operation, thereby reducing average power dissipation compared to a continuously active bypass circuit.
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.