MTJ Non-Volatile Memory Circuit for Low-Latency FPGA Initialization
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Solution Overview
Problem
The initialization of field-programmable gate arrays (FPGAs) is hindered by significant latency and energy consumption during the transfer of configuration patterns from non-volatile memory to internal configuration static random-access memory, which is not adequately addressed by existing power-reduction methods.
Innovation Solution
The implementation of a memory circuit comprising programmable non-volatile and volatile memory cells, utilizing magnetic tunnel junction (MTJ) devices and select devices, which allows for efficient programming and transfer of bit values through voltage levels, enabling reduced power and latency by using thermal assisted switching and spin torque transfer techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If configuration patterns are transferred from non-volatile memory to internal configuration SRAM through regular data pins, then the transfer can be performed using conventional methods, but significant latency and energy consumption occur during initialization
Solution Approach 1:
The memory cell is divided into two distinct parts: a non-volatile memory (NVM) cell for storing configuration bits and a volatile memory (VM) cell for rapid access. This segmentation allows the NVM to retain configuration data without power while the VM provides fast readout during initialization, thereby reducing both latency and energy consumption during the transfer process.
Solution Approach 2:
The NVM cell pre-stores the configuration pattern before the FPGA is powered on or before initialization is needed. This preliminary action eliminates the need to transfer large amounts of data during startup, as the configuration is already prepared and can be quickly loaded into the VM cell when needed, reducing initialization latency and energy usage.
2Reliability
If NVM cell is embedded within the FPGA chip, then secure independent configuration storage is provided, but the transfer process during power-up still requires conventional data transfer methods with high power consumption
Solution Approach 1:
The NVM cell and VM cell are merged into a single integrated memory structure where the NVM cell stores configuration bits and the VM cell provides rapid readout. This combination allows the configuration data to be securely stored within the FPGA chip while enabling low-power, fast transfer during initialization by utilizing the VM cell's efficient readout path rather than conventional data pin transfers.
Solution Approach 2:
The VM cell acts as an intermediary between the NVM cell and the rest of the FPGA configuration system. During initialization, the VM cell receives data from the NVM cell and provides it to the configuration logic, enabling efficient data transfer with reduced power consumption compared to direct transfers through conventional data pins.
3Ease of manufacture
If conventional data transfer methods are used for initialization, then the transfer process is simple to implement, but significant power and time resources are consumed
Solution Approach 1:
The memory circuit dynamically switches between different operational modes: during normal operation, the NVM cell holds configuration data; during initialization, the VM cell is activated to rapidly readout the configuration. This dynamic operation allows the system to achieve fast initialization speeds while maintaining implementation simplicity by using standard memory cell structures and control logic.
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
This approach significantly reduces the power and duration of the initialization process, providing a low-energy, distributed configuration capability with minimal silicon area and process complexity, while maintaining system reliability and compatibility with lower supply voltages.
Implementation Method 1
enabling reduced power and latency by using thermal assisted switching and spin torque transfer techniques
Implementation Method 2
enabling reduced power and latency by using thermal assisted switching and spin torque transfer techniques
Data Source
AI summary
One aspect relates to a memory circuit that has a programmable non-volatile memory (NVM) cell configured to generate an NVM output signal indicative of a program state of the NVM cell and to configure a volatile output based on the program state of the NVM cell. The NVM cell comprises a first magnetic tunnel junction (MTJ) device, a first select device connected in series with the first MTJ device at a first node, and a first pass device. The memory circuit also may have a programmable (independently of the NVM cell) volatile memory (VM) cell configured to receive the NVM output signal at a VM input node and to generate a VM output signal indicative of the program state of the VM cell.