Dual-Path Level Shifter for Duty Cycle Distortion Cancellation
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Solution Overview
Problem
Conventional level shifter designs introduce duty cycle distortion when translating signals across different voltage domains, leading to inaccuracies in stepped-up or stepped-down output signals.
Innovation Solution
A dual path level shifter circuit is designed, comprising two series-connected paths of inverters connected to different voltage supplies, where one path generates a positive duty cycle distortion and the other a negative distortion, which are combined to eliminate duty cycle distortion in the output signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional level shifter design uses multiple voltage supplies with series-connected inverters, then signal translation between voltage domains is achieved, but duty cycle distortion is introduced in the output signal
Solution Approach 1:
The level shifter is divided into two separate paths (first path and second path), each processing the input signal independently through series-connected inverters. This segmentation allows the distortions from each path to be averaged, reducing the overall duty cycle distortion in the combined output signal.
Solution Approach 2:
The output signals from the first path and second path are merged together to produce the final output signal. By combining the two paths with opposite duty cycle distortions, the harmful effects cancel each other out, achieving both voltage domain translation and duty cycle accuracy.
2Adaptability or versatility
If multiple voltage supplies are used in the level shifter circuit, then signal level translation is enabled, but the circuit complexity increases
Solution Approach 1:
The circuit is segmented into two symmetric paths with inverters distributed across different voltage supplies. This segmentation provides flexibility in voltage domain translation while maintaining a regular, predictable circuit structure that is easier to design and analyze.
Solution Approach 2:
The two paths are designed with asymmetric connections to voltage supplies (different numbers of inverters connected to different supplies), which creates complementary duty cycle distortions that cancel when combined, achieving both versatility and manageable complexity.
Data Source
AI summary
A level shifter circuit comprises a first and second path connected in parallel. The first path comprises three inverters connected in series, and the first path generates a first intermediate clock signal based on an input clock signal. The first intermediate clock signal has a first duty cycle distortion. The second path also comprises three inverters connected in series and the second path generates a second intermediate clock signal based on the input clock signal. The second intermediate clock signal has a second duty cycle distortion. A level shifter output provides an output clock signal based on a combination of the first and second intermediate clock signals. The combination of the first and second intermediate clock signals results in an averaging of the first and second duty cycle distortions in the output clock signal.