AC-Coupled Voltage Level Shifter for Low-Latency Interfaces
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Solution Overview
Problem
Conventional voltage level shifters suffer from high latency, inconsistent performance, and duty cycle distortion in high-speed interface applications, particularly when dealing with extreme voltage level combinations, which limits their effectiveness in modern integrated circuits with varying supply voltages.
Innovation Solution
A low latency, low distortion voltage boost circuit is employed, utilizing an AC-coupled voltage boost circuit with CMOS inverters and switches to efficiently shift low voltage signals to high voltage levels, reducing power consumption and latency while maintaining consistent performance across different operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional voltage level shifters are used to interface between low and high voltage sections, then voltage level shifting is achieved, but high latency is introduced
Solution Approach 1:
The patent implements dynamic voltage boosting by activating the voltage boost circuit only when the input signal transitions to a high logic level. The circuit switches between normal pass-through mode and voltage boosting mode based on signal conditions, thereby reducing latency during critical transitions while maintaining performance consistency across varying voltage levels and operating conditions.
2Ease of operation
If conventional voltage level shifters are used, then voltage level shifting is achieved, but duty cycle distortion occurs
Solution Approach 1:
The voltage boost circuit is activated in advance of the actual signal transition it is intended to assist. By detecting the rising edge of the input signal and pre-charging the boost capacitor, the circuit ensures that the voltage boosting effect is already in place when needed, thereby preventing duty cycle distortion without requiring complex feedback mechanisms.
3Adaptability or versatility
If voltage level shifting is performed across extreme voltage combinations, then interface compatibility is achieved, but inconsistent performance occurs
Solution Approach 1:
The patent dynamically adjusts the voltage boosting parameter (the amount of voltage added to the input signal) based on the detected voltage levels of both the input and output sections. By changing the operating parameters of the voltage boost circuit adaptively, the system maintains consistent performance across extreme voltage combinations such as 1.0V to 3.3V interfaces, rather than relying on fixed voltage transformation ratios.
Data Source
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AI summary
Certain aspects of the present disclosure provide a voltage level shifting circuit employing a low latency, AC-coupled voltage boost circuit, as well as other circuits and apparatus incorporating such a level shifting circuit. Such level shifting circuits provide significantly lower latency compared to conventional level shifters (e.g., latency reduced by at least a factor of two). Offering consistent latency over the simulation corners, level shifting circuits described herein also provide significantly lower power consumption and reduced duty cycle distortion compared to conventional level shifters.