USB Repeater Skew Detector Circuit to Block False High-Speed Noise
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Solution Overview
Problem
In eUSB/USB2 repeaters, skewed low-speed and full-speed signals cause unwanted high-speed noise due to incorrect detection of signal skew, leading to false enabling of the high-speed path, which results in noise on the USB2 output, and existing solutions are complex, power-hungry, and area-intensive.
Innovation Solution
A low-area, low-current, low-complexity skew detector circuit using a NAND gate with two level shifters and a voltage regulator to generate necessary voltages, ensuring fast response and accurate detection of signal skew without false enabling of the high-speed path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a skew detector circuit is implemented to detect signal skew, then high-speed noise is prevented, but power consumption and area usage increase
Solution Approach 1:
The voltage regulation function is segmented into multiple stages with different voltage levels (first voltage for logic circuit, second voltage for first level shifter, third voltage for second level shifter). This segmentation allows each component to operate at its optimal voltage level, reducing overall power consumption while maintaining noise prevention capability
Solution Approach 2:
The patent changes the voltage parameter across different circuit stages by using a voltage regulator to generate multiple voltage levels. The logic circuit operates at a lower first voltage, while level shifters operate at progressively higher voltages, optimizing the balance between noise immunity and power consumption
2Object-affected harmful factors
If a skew detector circuit is implemented to detect signal skew, then high-speed noise is prevented, but device area increases
Solution Approach 1:
The circuit is segmented into functional modules (logic circuit, level shifters, voltage regulator) that can be independently optimized and laid out. This modular segmentation reduces interconnections and allows for more compact area utilization while maintaining the complete skew detection functionality
Solution Approach 2:
The patent uses multiple voltage levels (first voltage, second voltage, third voltage) as an additional dimension to reduce the area of individual circuit components. By operating different stages at different voltages, transistors can be sized more efficiently, reducing the overall area required for the same performance
3Measurement precision
If a skew detector circuit is implemented to detect signal skew, then signal skew detection accuracy is improved, but device complexity increases
Solution Approach 1:
The skew detection function is segmented into a logic circuit for differential signal processing and level shifters for voltage level adaptation. This segmentation simplifies each individual block's design while maintaining overall detection accuracy through the coordinated operation of multiple specialized stages
Solution Approach 2:
Level shifters are introduced as intermediary components between the logic circuit and the output stage. These intermediaries handle the voltage level transitions, allowing the logic circuit to focus solely on skew detection logic, thereby simplifying the overall design while improving detection accuracy
Data Source
AI summary
Various embodiments relate to a skew detector circuit, including: a logic circuit having two inputs configured to generate a logic 1 output when the two inputs have a logic 0 value and generator a logic 0 output when the two input have a logic 1 value; a first level shifter configured to increase the output of the logic circuit to a higher voltage; a second level shifter configured to increase the output of the first level shifter to a higher voltage; and a voltage regulator configured to produce a first voltage for the logic circuit, a second voltage for the first level shifter, and a third voltage for the second level shift.