SRAM Pre-Charge Circuit Layout for Lower Bitline Power Draw
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Solution Overview
Problem
Existing static random access memory (SRAM) technologies face challenges in optimizing power consumption and efficiency during pre-charge operations, particularly in high-speed data access applications like cache memory, where the pre-charge circuits contribute significantly to power consumption.
Innovation Solution
The introduction of a pre-charge circuit with various transistor configurations, including PFET and NFET devices, that minimize power consumption by eliminating the need for NFET devices connected to ground voltage, thereby reducing power draw during signal toggling, and incorporating a write assist cell to enhance memory write operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional SRAM pre-charge circuit is used, then bitline can be charged for read/write operations, but voltage drops occur and power consumption increases due to control signal toggling
Solution Approach 1:
The pre-charge circuit is divided into multiple pre-charge cells (first pre-charge cell and second pre-charge cell) that operate independently. Each cell handles specific charging tasks, allowing the system to maintain voltage stability without requiring all cells to toggle simultaneously, thereby reducing overall power consumption.
Solution Approach 2:
The pre-charge cells perform preliminary charging of bitlines before actual read or write operations occur. By pre-charging the bitlines to the appropriate voltage levels in advance, the circuit avoids voltage drops during operations and reduces the need for frequent control signal toggling, thus lowering power consumption.
2Productivity
If multiple pre-charge cells are added to improve pre-charge efficiency, then power consumption should decrease, but device complexity increases
Solution Approach 1:
The pre-charge function is segmented into multiple independent cells that can operate in parallel. This segmentation improves pre-charge efficiency by allowing simultaneous charging of different bitlines while keeping each individual cell relatively simple, thus balancing productivity improvement with acceptable complexity.
Solution Approach 2:
The pre-charge cells are arranged in a stacked configuration where smaller functional units are nested within a larger structural framework. This nesting approach allows multiple pre-charge cells to share common control logic and interconnection structures, improving efficiency while minimizing the increase in overall device complexity.
Data Source
AI summary
The present disclosure describes embodiments of a memory device with a pre-charge circuit. The memory device can include a memory cell, and the pre-charge circuit can include a first transistor and a second transistor. The first transistor includes a first gate terminal, a first source/drain (S/D) terminal coupled to a reference voltage, and a second S/D terminal coupled to a first terminal of the memory cell. The second transistor includes a second gate terminal, a third S/D terminal coupled to the reference voltage, and a fourth S/D terminal coupled to the second terminal of the memory cell. The first and second transistors are configured to pass the reference voltage in response to the control signal being applied to the first and second gate terminals, respectively.