SRAM Precharge Circuit Control for Write Cycle Power Reduction
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Solution Overview
Problem
The precharge operation in SRAM memory devices is a significant contributor to dynamic power consumption, especially during write operations, as bit lines are often precharged regardless of the pending operation, leading to inefficiencies in smaller and more portable devices.
Innovation Solution
Implementing a control circuit that determines the pending operation and only precharges bit lines for read operations, allowing bit lines to remain floating during write operations, thereby reducing power consumption by disabling precharge circuitry during write cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bit lines are precharged before every operation, then read operations can be performed correctly, but power consumption increases during write operations
Solution Approach 1:
The precharge operation is made dynamic by conditioning it on the type of operation being performed. The control circuit dynamically enables precharge only when a read operation is detected, and disables it during write operations, transforming a static always-on precharge mechanism into a dynamic conditional operation.
Solution Approach 2:
The precharge operation parameter is changed from a fixed state (always precharge) to a variable state (precharge only when needed). The control circuit changes the precharge parameter based on the operation type detected, enabling precharge for reads and disabling it for writes.
2Ease of operation
If precharge circuitry is always enabled, then bit lines are ready for any operation, but dynamic power consumption increases
Solution Approach 1:
Instead of continuous precharging, the system uses periodic action by enabling precharge only during the periods when read operations occur. The control circuit creates periodic precharge cycles synchronized with read operations, leaving bit lines floating during write operations to reduce energy loss.
Solution Approach 2:
The unnecessary precharge operation is extracted and removed from the write operation sequence. The control circuit identifies and eliminates the redundant precharge step that occurs before write operations, keeping bit lines floating instead of precharging them when not needed.
3Reliability
If bit lines are precharged for all operations, then operation reliability is maintained, but energy efficiency decreases in portable devices
Solution Approach 1:
The control circuit uses feedback from the operation type signal to determine whether to enable or disable precharge. The system receives feedback about whether a read or write operation is pending and adjusts the precharge operation accordingly, ensuring reliability for reads while saving energy during writes.
Solution Approach 2:
The control circuit automatically determines the appropriate precharge action based on the operation type without requiring external intervention. The system serves itself by autonomously enabling or disabling precharge based on the detected operation, improving energy efficiency while maintaining reliability.
Data Source
AI summary
A memory having a memory array having bit cells coupled to bit lines. The memory further includes a precharge circuit that precharges bit lines. The memory also includes a control circuit coupled to the precharge circuit that enables the precharge circuit at a beginning portion of a read cycle, keeps the precharge circuit disabled until an end of the read cycle, and keeps the precharge circuit disabled during a write cycle. A method of operating a memory, in which the memory includes an array of memory cells coupled to bit lines, includes precharging the bit lines at a beginning of a read cycle. The method also includes blocking precharging of the bit lines for a duration of a write cycle.