Explicit Skew Interface for Crosstalk and SSO Noise Reduction
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Solution Overview
Problem
In electronic systems, high-frequency data transmission between integrated circuits often results in crosstalk and simultaneous switching noise, which degrade signal quality and lead to errors, particularly in multi-element data transmission.
Innovation Solution
A pre-skewing scheme is implemented where the first chip transmits data elements at different times, and the second chip receives and processes these elements using a receiver circuit with a linear clock tree and input latches, synchronizing the data elements to arrive simultaneously, thereby reducing crosstalk and SSO noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple data elements are transmitted simultaneously through parallel channels, then data transmission rate is improved, but crosstalk and SSO noise increase degrading signal quality
Solution Approach 1:
The transmitter applies pre-skewing to data elements before transmission, intentionally introducing timing offsets in advance. This preliminary action ensures that data elements do not transition simultaneously during transmission, thereby preventing crosstalk and SSO noise from occurring in the first place, while still maintaining high data transmission rates through parallel channels
Solution Approach 2:
The system uses periodic clock signals with different phases to control the transmission timing of data elements. By assigning different phase relationships to different data elements, the system creates a periodic transmission pattern that avoids simultaneous transitions, reducing noise while maintaining efficient parallel data transmission
2Speed
If data transmission frequency is increased to improve speed, then productivity is improved, but crosstalk and SSO noise adversely affect signal quality resulting in errors
Solution Approach 1:
Pre-skewing is applied to data elements before high-frequency transmission, intentionally staggering their timing in advance. This preliminary timing adjustment ensures that even at increased transmission frequencies, data elements do not transition simultaneously, thereby maintaining signal quality and reliability while achieving higher data transmission speeds
Solution Approach 2:
The system changes the timing parameters of data element transmission by applying different skew amounts to different elements. This parameter modification allows the system to operate at higher frequencies without suffering from noise-induced errors, as the skewed timing parameters prevent simultaneous transitions that would otherwise degrade signal quality
3Object-affected harmful factors
If data elements are transmitted at different times to reduce noise, then crosstalk and SSO noise are reduced, but timing synchronization becomes more complex
Solution Approach 1:
A dedicated skew control circuit acts as an intermediary between the data source and transmission channels. This intermediary component automatically applies the appropriate pre-skewing to each data element based on its position, eliminating the need for complex timing coordination logic elsewhere in the system and simplifying overall synchronization while still reducing noise
Solution Approach 2:
The pre-skewing mechanism is designed to automatically adjust timing offsets for each data element without requiring external intervention or complex coordination. Each data element self-adjusts its transmission timing through the skew circuit based on its position in the parallel bus, reducing noise while keeping the synchronization mechanism simple and self-contained
Data Source
AI summary
Methods and apparatus are disclosed, such as those involving an inter-chip interface configured to receive and process electronic data. One such interface includes a receiver circuit that includes a clock tree configured to receive a clock signal at a clock tree input. The clock tree distributes a plurality of clock signals delayed from the clock signal such that one or more of the clock signals have a delay different from the delays of the other clock signals. The receiver circuit further includes a plurality of data input latches configured to receive a plurality of data elements over two or more different points in time. This configuration at least partially reduces crosstalk and simultaneous switching output noise.