Data Bus Inversion Vector Control for SSO Reduction
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Solution Overview
Problem
Data bus inversion (DBI) techniques can introduce new simultaneous switching output (SSO) problems and reduce the overall SSO benefit in computing systems, especially when power consumption is asymmetric between data states, leading to increased DC power consumption and noise.
Innovation Solution
Implementing a global data bus inversion indicator that groups data bus inversion indicators into a vector and communicates this indicator separately from data transfers, using a sideband signal or data mask line, to control and minimize SSO transitions across multiple data time slots.
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 savings are achieved, but simultaneous switching output (SSO) problems are introduced and noise increases
Solution Approach 1:
The data bus is segmented into multiple groups, with each group having its own inversion control. This allows selective inversion of specific bus groups rather than the entire bus, enabling power optimization for individual groups while maintaining SSO control for others, thus resolving the contradiction between power savings and SSO reduction
Solution Approach 2:
The inversion control is made dynamic by allowing the controller to selectively enable or disable inversion on different bus groups based on current operating conditions. This dynamic control enables the system to optimize power consumption when needed while avoiding SSO problems in other scenarios
2Use of energy by moving object
If data bus inversion is applied to reduce DC power consumption, then power savings are achieved, but device complexity increases
Solution Approach 1:
The inversion control mechanism is designed to be universal, allowing the same control logic to manage multiple bus groups with different inversion requirements. This multi-functionality reduces the need for separate control circuits for each bus group, thereby limiting the increase in device complexity while maintaining power optimization capabilities
Data Source
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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.