Multiplexer Tree Input Fixing for Lower PLD Power
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Solution Overview
Problem
Programmable logic devices (PLDs) exhibit high static and dynamic power consumption due to unused resources and hardware overhead, making them unsuitable for low-power applications like portable devices.
Innovation Solution
The method involves determining unused selection inputs in a multiplexer tree, pulling them to a constant value, and assigning predetermined values to unused data inputs to prevent toggling and reduce leakage current, thereby optimizing power usage without affecting logic functionality or timing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PLDs use a subset of available resources for a given design, then mapping flexibility is improved, but static power consumption increases due to leakage current from unused resources
Solution Approach 1:
The patent extracts and removes the harmful effect of leakage current by detecting unused selection inputs and actively pulling them to a constant logic value. This separates the functional resources from the non-functional ones, allowing the unused portion to be electrically deactivated while maintaining the physical structure for future flexibility.
Solution Approach 2:
The patent changes the electrical state parameter of unused resources by transitioning selection inputs from floating or indeterminate states to fixed constant values (logic 0 or logic 1). This parameter change effectively turns off the leakage current path while preserving the physical resource structure for potential future use.
2Adaptability or versatility
If PLDs include hardware overhead for user programmability, then adaptability is improved, but dynamic power consumption increases
Solution Approach 1:
The patent extracts the unnecessary switching activity from the system by detecting when selection inputs are unused and eliminating their toggling behavior. This removes the dynamic power consumption associated with redundant switching operations while preserving the programmable logic structure.
Solution Approach 2:
The patent changes the temporal behavior parameter of unused selection inputs by fixing them to constant values, thereby eliminating transitions and switching activity. This parameter change from variable to constant state directly reduces dynamic power consumption while maintaining the device's programmable nature.
3Reliability
If data inputs in a multiplexer tree toggle unnecessarily, then logic functionality is maintained, but dynamic power consumption increases
Solution Approach 1:
The patent performs preliminary detection of unused selection inputs before the unnecessary toggling can occur. By identifying and fixing these inputs in advance, the system prevents the cascading effect that would cause data inputs to toggle unnecessarily, thereby eliminating dynamic power waste before it happens.
Solution Approach 2:
The patent changes the state parameter of unused selection inputs from variable to constant, which propagates through the multiplexer tree to stabilize data inputs. This parameter change eliminates the need for unnecessary toggling while preserving the ability to select correct data paths when needed.
Data Source
AI summary
A method of reducing power of a circuit is described. The method includes determining at least one unused selection input associated with stages of a multiplexer tree; pulling the at least one unused selection input to a constant value; and assigning predetermined values to unused data inputs of the multiplexer tree associated with the at least one unused selection input.