Resistive Memory Write Read Power Optimization
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Solution Overview
Problem
Resistive memories, such as STT-MRAM, consume high static power during write operations and may also consume static read power, leading to inefficiencies in energy usage, especially when the write current is larger than the read current and read operations are slower than write operations.
Innovation Solution
Implementing data-driven write techniques with asymmetric write switch currents, self-controlled write and read operations, and performing read operations before write operations to reduce power consumption by optimizing write and read pulse durations and currents, and stopping operations once the bit-cell flips or data is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional write operations are used in resistive memory, then write capability is achieved, but power consumption is high due to large write current
Solution Approach 1:
The patent performs a read operation before the write operation to check if the data needs to be written. This preliminary action avoids unnecessary write operations, reducing write energy consumption by 25% to 37% when the read data matches the write data.
Solution Approach 2:
The patent uses asymmetric write switch currents where different current magnitudes are applied depending on the write condition. The write current is optimized to be just sufficient for the required operation, avoiding excessive current application, which reduces power consumption while maintaining write capability.
2Use of energy by moving object
If conventional read operations are used in resistive memory, then read capability is achieved, but power consumption is high due to static read power
Solution Approach 1:
The patent implements self-controlled read operations where the read operation automatically stops once the data is detected. This self-service mechanism eliminates the need for continuous power supply during the read operation, reducing read power consumption by 10% to 25%.
Solution Approach 2:
The patent uses pulsed read operations instead of continuous read operations. The read current is applied in periodic pulses only when needed, rather than continuously, which significantly reduces the static read power consumption while maintaining read capability.
3Reliability
If fixed pulse durations are used for write operations, then write reliability is ensured, but energy efficiency is reduced due to unnecessary writes
Solution Approach 1:
The patent performs a read operation before the write operation to verify if the write is necessary. This preliminary check ensures write reliability by confirming the data state before writing, while simultaneously reducing write energy by avoiding redundant write operations.
Solution Approach 2:
The patent uses the read operation result as feedback to control whether the write operation should proceed. This feedback mechanism ensures that writes are only performed when necessary, maintaining reliability while optimizing energy efficiency.
Data Source
AI summary
Described are apparatuses for improving resistive memory energy efficiency. An apparatus performs data-driven write to make use of asymmetric write switch energy between write0 and write1 operations. The apparatus comprises: a resistive memory cell coupled to a bit line and a select line; a first pass-gate coupled to the bit line; a second pass-gate coupled to the select line; and a multiplexer operable by input data, the multiplexer to provide a control signal to the first and second pass-gates or to write drivers according to logic level of the input data. An apparatus comprises circuit for performing read before write operation which avoids unnecessary writes with an initial low power read operation. An apparatus comprises circuit to perform self-controlled write operation which stops the write operation as soon as bit-cell flips. An apparatus comprises circuit for performing self-controlled read operation which stops read operation as soon as data is detected.