Memory Macro Address Mapping to Reduce Address Bus Toggle Power
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing memory systems dissipate power due to unnecessary toggling of memory macro address buses, particularly when input addresses are outside the mapped address range, leading to inefficient power consumption.
Innovation Solution
Implement bipartite-parking address mappers that prevent access to memory macros when input addresses are outside their mapped ranges, maintaining the address bus at a fixed value to reduce toggling, and apply encoding methods like Gray coding and bit swapping to further minimize power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the memory macro address bus is allowed to toggle freely to accommodate all input addresses, then the memory system can access any address range, but power is dissipated due to unnecessary toggling when addresses are outside the mapped range
Solution Approach 1:
The address mapper performs preliminary mapping of input addresses to memory macro addresses before actual memory access occurs. When an input address falls outside the mapped range, the mapper proactively sets the address bus to a predetermined value (such as the first or last address in the range) in advance, preventing unnecessary toggling when the address transitions back into the valid range.
Solution Approach 2:
The system changes the state parameter of the address bus from a freely toggling state to a constrained state with predetermined values. By modifying the address mapping parameters to include clamping behavior for out-of-range addresses, the system reduces address bus transitions while maintaining correct memory access functionality for valid addresses.
2Use of energy by moving object
If the address bus is clamped to predetermined values for out-of-range addresses, then power consumption is reduced by preventing unnecessary toggling, but the address mapper complexity increases
Solution Approach 1:
The address mapping function is segmented into distinct operational modes: one mode for handling addresses within the valid mapped range (normal mapping operation) and another mode for handling addresses outside the range (clamping to predetermined values). This segmentation allows the address mapper to use simple conditional logic rather than a fully complex mapping function, potentially reducing overall circuit complexity while achieving power savings.
3Loss of energy
If traditional address mapping is used without clamping, then the address bus accurately reflects all input addresses, but each toggle of the address bus dissipates power, especially for LSB which accounts for 50% of all toggles
Solution Approach 1:
The address bus is clamped to predetermined values only partially - specifically when input addresses fall outside the mapped range. For addresses within the valid range, the address bus maintains accurate reflection of the input address. This partial application of clamping reduces energy loss from unnecessary toggles while preserving address accuracy where needed, accepting minimal excessive action in the form of clamped values that never actually occur during normal operation.
Data Source
AI summary
A memory device includes a first address mapper and a first memory macro connected to the first address mapper. The first address mapper is configured to identify an input address that does not fall within a first address range mapped to the first memory macro, and in response to identifying that the input address does not fall within the first address range mapped to the first memory macro, prevent access to the first memory macro and set an address bus of the first memory macro to a value that depends on whether the input address is lower or higher than the first address range.