Magnetic LUT Bank Architecture for Low-Power FPGA Mapping
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Solution Overview
Problem
Conventional Look Up Tables (LUTs) in Field Programmable Gate Arrays (FPGAs) face challenges in reducing circuit area and power consumption, limiting their ability to configure combinational logic circuits efficiently and operate at high speeds due to the use of static RAMs and magnetic elements that require continuous power and result in large parasitic capacitance and slow operation.
Innovation Solution
A LUT design incorporating a decoder, storage units with magnetic elements, and a signal input/output unit that allows for efficient selection and programming of magnetic elements, along with a technology mapping method that converts gate-level netlists into AND-Inverter Graphs and selects optimal cuts to minimize area and power consumption, enabling immediate signal changes and reduced static current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetic elements are used in LUT to replace SRAM, then nonvolatile storage is achieved, but circuit area and static current increase
Solution Approach 1:
The LUT is divided into multiple banks, each containing a subset of the magnetic elements. This segmentation allows the circuit to activate only the necessary banks for a given operation, reducing the effective circuit area and static current consumption while maintaining nonvolatile storage capability across all banks
Solution Approach 2:
The patent introduces a bank selection mechanism that adds a dimensional layer to the LUT architecture. Instead of a flat array of magnetic elements, the structure is organized into multiple banks that can be independently selected and activated, effectively managing the trade-off between storage capacity and active circuit area
2Reliability
If magnetic elements are used in LUT, then nonvolatile storage is achieved, but operation speed decreases due to large parasitic capacitance
Solution Approach 1:
By segmenting the LUT into multiple smaller banks, the parasitic capacitance of each individual bank is reduced. This allows for faster switching and operation speeds within each bank, while the overall LUT maintains its nonvolatile storage capacity across all banks
Solution Approach 2:
The patent implements dynamic bank selection where only the necessary banks are activated for each operation. This dynamic approach reduces the total parasitic capacitance involved in each switching event, thereby improving operation speed while preserving the nonvolatile characteristics of the magnetic elements
3Ease of operation
If sense amplifier is activated and deactivated frequently to change output signal, then LUT circuit can operate, but configuration of combinational logic circuit becomes difficult and operation speed is limited
Solution Approach 1:
The patent pre-charges the selected magnetic element before reading its state. This preliminary action ensures that the output signal can change immediately in response to input signal changes, enabling true combinational logic operation without requiring frequent sense amplifier activation and deactivation
Solution Approach 2:
The continuous pre-charge mechanism maintains the circuit in a ready state, allowing immediate response to input changes. This eliminates the need for repeated activation/deactivation cycles of the sense amplifier, enabling both combinational logic configuration and high-speed operation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution reduces circuit area and power consumption, allowing for efficient configuration of both combinational and sequential logic circuits with improved operation speed and immediate signal changes, while minimizing static current and power consumption.
Implementation Method 1
a storage unit including a plurality of magnetic elements and configured to select one or more of the plurality of magnetic elements
Data Source
AI summary
A look up table (LUT) includes a decoder configured to decode input signals and to output decoded signals, a storage unit including a plurality of magnetic elements an being configured to select one or more of the plurality of magnetic elements in response to the decoded signals and a signal input/output (TO) unit configured to output an output signal corresponding to the selected one or more magnetic elements and to program the selected one or more magnetic elements by receiving a write signal.