Data Bus Inversion Signaling for Lower SSO Memory Buses
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Solution Overview
Problem
Data bus inversion (DBI) techniques can introduce new simultaneous switching output (SSO) problems while attempting to reduce DC power consumption in computing systems, particularly in systems where transmitting 1s is lower power than transmitting 0s, leading to reduced overall SSO benefits.
Innovation Solution
The implementation of a global data bus inversion indicator and a data bus inversion vector, where the global DBI bit is used to control and invert the DBI vector, minimizing SSO transitions by strategically communicating the DBI indicators through sideband signals or data slots, and adjusting DBI application across data and address buses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If data bus inversion is applied to reduce DC power consumption, then power consumption is reduced, but simultaneous switching output problems are introduced
Solution Approach 1:
The patent segments the data bus into multiple independent data lines and applies inversion selectively to individual lines based on their switching patterns, rather than inverting the entire bus uniformly. This segmentation allows optimization of power consumption on a per-line basis while controlling SSO transitions through coordinated but independent inversion decisions for each data line.
Solution Approach 2:
The patent dynamically changes the inversion parameter (whether to invert a data line) based on real-time analysis of switching patterns and power consumption characteristics of each data line. By monitoring the number of transitions and power consumption metrics, the system adjusts inversion decisions to minimize total power consumption while keeping SSO transitions within acceptable limits.
2Use of energy by moving object
If data bus inversion is applied to reduce power consumption, then power consumption is reduced, but noise performance deteriorates
Solution Approach 1:
The patent applies different inversion strategies to different data lines based on their local characteristics, such as switching frequency, power consumption patterns, and coupling with other lines. By analyzing the specific noise contribution of each line and its inversion pattern, the system optimizes inversion decisions locally to reduce power consumption while minimizing noise impact on the overall bus.
3Use of energy by moving object
If data bus inversion is applied to reduce power consumption, then power consumption is reduced, but memory bus frequency increases cooling requirements
Solution Approach 1:
The patent implements a dynamic inversion control mechanism that continuously monitors bus activity patterns, power consumption, and temperature conditions. The inversion strategy adapts in real-time to changing operating conditions, adjusting which data lines are inverted based on current thermal state and activity patterns, thereby reducing power consumption and heat generation dynamically rather than using a fixed inversion pattern.
Data Source
AI summary
An apparatus includes a plurality of data lines defining a data bus for communicating data. A controller is operable to communicate a plurality of data transfers over the data bus using a plurality of data time slots, wherein for at least a subset of the data time slots the controller is operable to communicate an associated data bus inversion indicator indicating that bits communicated during the associated data time slot are inverted, the data bus inversion indicators for the subset of the data transfers are grouped into a data bus inversion vector, and the controller is operable to communicate a global data bus inversion indicator indicating an inversion of the data bus inversion vector.