Low-Skew Channel Bonding via Oversampling and Bit-Slip Control
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Solution Overview
Problem
Conventional high-speed serial interface bonding techniques face challenges in achieving low channel-to-channel skew, especially at higher data rates, as they often introduce additional jitter and are not scalable to higher frequencies.
Innovation Solution
The method employs oversampling for low-skew bonding of data channels by using higher-speed outgoing data paths and slower-speed return data paths, with a channel-bonding control circuit measuring skew and generating bit-slip or word-slip control signals to compensate, thereby avoiding the introduction of jitter and supporting bonding across non-adjacent channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional HSSI bonding techniques are used, then channel bonding is achieved, but additional jitter is introduced and skew control becomes difficult at higher data rates
Solution Approach 1:
The patent replaces conventional analog skew adjustment mechanisms with a digital oversampling approach. By sampling the returned data signals at multiple points within each unit interval and selecting the valid sample, the system achieves skew compensation without introducing jitter, fundamentally changing the mechanism from mechanical/analog adjustment to digital signal processing
Solution Approach 2:
The patent changes the sampling rate parameter by using oversampling (sampling at a rate higher than the minimum required). This parameter change allows the system to tolerate skew without introducing jitter, as the oversampled signals provide multiple opportunities to capture valid data within each unit interval, effectively resolving the contradiction between skew control and jitter generation
2Speed
If conventional bonding techniques are used at higher data rates, then data transmission speed increases, but skew measurement and compensation becomes more challenging
Solution Approach 1:
The patent performs preliminary oversampling of the returned data signals before skew measurement and compensation. By pre-sampling the signals at multiple points within each unit interval and identifying valid samples in advance, the system simplifies subsequent skew measurement and compensation operations, making them more tractable even at higher data rates
Solution Approach 2:
The patent substitutes complex high-speed skew measurement and adjustment mechanisms with a simpler digital oversampling approach. The oversampled valid signal selection process replaces complicated real-time skew measurement and adjustment circuitry, making the system more manageable at higher data rates while maintaining measurement precision
Data Source
AI summary
In accordance with an embodiment of the invention, higher-speed outgoing data paths are used to transmit oversampled data signals, and corresponding slower-speed return data paths are used to receive return data signals. A channel-bonding control circuit measures the skew between the returned data signals and generates bit-slip and/or word-slip control signals to compensate for the skew. Transmission bit-slip (or, alternatively, clock-slip) circuits slip integer numbers of bits based on the bit-slip control signals. Bypass registers (or, alternatively, FIFO write or read enable signals) may be used to slip a whole word when the integer number of bits to slip is greater or equal to the parallel width of a lane. Various other aspects, features, and embodiments are also disclosed.