Deskew Circuit for Asymmetric Edge Delay Compensation
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Solution Overview
Problem
In computer systems, especially in mobile applications, signal skew between data and strobe signals leads to setup and hold window shifts during sampling, which can result in unreliable receiver performance and increased power consumption, particularly due to process, temperature, and voltage variations.
Innovation Solution
A deskew circuit is implemented to receive signals with delayed edges and provide deskewed outputs, where the difference between the fourth delay and the third delay is equal to the difference between the first delay and the second delay, effectively offsetting these variations and stabilizing the setup and hold windows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If I/O data bit and strobe signal speeds are increased to build higher bandwidth communication links, then data transmission speed is improved, but signal skew through the receivers increases leading to setup and hold window shifts
Solution Approach 1:
The patent applies preliminary action by introducing a deskew circuit that pre-compensates for signal skew before the signals reach the receiver. The deskew circuit calculates expected skew based on process, temperature, and voltage conditions, and applies compensatory delays to equalize the timing of data and strobe signals in advance, preventing setup and hold window shifts before they occur.
2Reliability
If more complex receiver designs are used to improve receiver performance, then signal reception accuracy is improved, but circuitry reliability decreases and power consumption increases
Solution Approach 1:
The patent introduces an intermediary deskew circuit between the communication link and the receiver. This mediator handles the complex skew compensation function separately, allowing the receiver itself to remain simple and reliable. The deskew circuit acts as a buffer that equalizes signals before they reach the receiver, improving reception accuracy without complicating the receiver design.
Solution Approach 2:
The deskew circuit implements self-service by using feedback from the receiver's skew detection to automatically adjust its compensation. The system monitors the actual skew conditions and dynamically adjusts the deskew circuit's delay parameters, allowing it to maintain optimal performance across varying process, temperature, and voltage conditions without external intervention or complex receiver design.
3Reliability
If more complex receiver designs are used to improve receiver performance, then signal reception accuracy is improved, but power consumption increases
Solution Approach 1:
The deskew circuit serves as an intermediary that handles the power-intensive skew compensation function separately from the receiver. By performing delay equalization in the deskew circuit rather than in the receiver, the system achieves improved signal reception accuracy while keeping the receiver's power consumption low. The deskew circuit can use efficient delay mechanisms that would be costly in terms of power if implemented within the receiver itself.
Data Source
AI summary
A circuit including a deskew circuit. The deskew circuit is configured to receive a first signal having a first edge delayed from a second edge of a second signal by a first delay and a third edge delayed from a fourth edge of the second signal by a second delay. The deskew circuit is configured to provide a third signal having a first deskewed edge delayed from the first edge by a third delay and a second deskewed edge delayed from the third edge by a fourth delay. The difference between the fourth delay and the third delay is substantially equal to the difference between the first delay and the second delay.