Dynamic Bus Inversion Using a Shared Strobe Line
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-speed data transfer in computer systems faces challenges such as signal integrity degradation due to excessive current change rates and signal timing issues, particularly in modem interfaces like DDR and GDDR, which lead to increased power consumption and complexity, and require additional pins and encoding schemes.
Innovation Solution
The implementation of a dynamic bus inversion (DBI) method and system that aligns sampling clocks using a forward strobe signal, allowing the strobe line to also transmit a DBI signal, eliminating the need for dedicated DBI pins and reducing complexity and bandwidth overhead, while achieving data rates similar to serial links without per-line closed-loop timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If all bits toggle at the same time to transmit data, then data transfer speed is improved, but signal integrity decreases due to excessive current change rates
Solution Approach 1:
The patent applies bus inversion by toggling the complement of the data bus instead of the data bus itself when more than half the bits need to change state. This inverts the toggling behavior to reduce the number of transitions, thereby reducing di/dt while maintaining data integrity through inversion indication bits.
Solution Approach 2:
The patent dynamically changes the bus state parameter by selecting between normal mode and inverted mode based on the number of bits that need to toggle. This parameter change allows optimization of current transition rates while maintaining correct data transmission through receiver-side decoding.
2Reliability
If dedicated DBI pins are added to indicate bus inversion, then signal integrity is improved, but device complexity and pin count increase
Solution Approach 1:
The patent merges the DBI indication function with existing data bits or control signals that are already transmitted on the bus. By combining multiple functions into existing signal paths, the patent eliminates the need for dedicated DBI pins while maintaining the ability to indicate bus inversion status.
Solution Approach 2:
The patent makes existing bus lines multi-functional by using them to carry both data and DBI indication information. This universal usage of existing signals eliminates the need for additional dedicated pins, reducing device complexity while maintaining signal integrity.
3Productivity
If more bits are toggled to transmit data, then data transfer efficiency is improved, but power consumption increases due to higher current change rates
Solution Approach 1:
The patent uses bus inversion to reduce the number of bit transitions by toggling the complement set of bits instead of the original set when more than half need to change. This reduces di/dt and associated power consumption while maintaining data transfer efficiency through proper inversion indication and decoding.
Solution Approach 2:
The patent dynamically adjusts the bus inversion parameter based on the data pattern being transmitted, selecting the mode (normal or inverted) that minimizes transitions for each transmission cycle. This dynamic parameter optimization reduces power consumption while maintaining high data transfer efficiency.
Data Source
AI summary
A dynamic bus inversion (DBI) method and system are described. In various embodiments, a transmitter transmits data over a multi-bit high-speed bus to a receiver. In an embodiment, the transmitter determines whether to invert the bus based on the number of data bits that will be transitioning to a new value. If it is determined that the bus is to be inverted, the transmitter encodes a DBI signal on a shared line of the bus. In an embodiment, the shared line is used for different purposes at different times, obviating the need for a dedicated line or pin for the encoded DBI signal. The receiver receives and decodes the DBI signal and, in response, appropriately decodes the received data.