Four-Transistor Data Latch Layout for Compact Flash Memory
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Solution Overview
Problem
The increasing bit density in flash memory due to multi-level cells and three-dimensional stacking leads to an increase in the area of peripheral circuits, particularly the data latch circuit, making it difficult to reduce the size of the flash memory chip.
Innovation Solution
A data latch circuit design using a reduced number of transistors, specifically four transistors, and a novel layout configuration that utilizes leakage current for data storage, reducing the circuit area and allowing for stable data retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the number of transistors in the data latch circuit is reduced, then the area of the peripheral circuit is reduced, but the stability of data storage may be compromised
Solution Approach 1:
The patent combines the data storage function and leakage current utilization into a single integrated circuit structure. The fourth transistor's leakage current is directly utilized to maintain the stored data state, eliminating the need for separate refresh circuits or additional transistors. This merging allows the circuit to achieve stable data retention with only four transistors, resolving the contradiction between reduced area and maintained reliability.
Solution Approach 2:
The patent converts the harmful leakage current, which typically causes data degradation in conventional latch circuits, into a beneficial mechanism for maintaining data stability. By designing the circuit so that the leakage current of the fourth transistor reinforces the stored data state, the circuit achieves reliable data retention with fewer transistors, thus resolving the contradiction between area reduction and reliability maintenance.
2Reliability
If conventional data latch circuit designs are used, then data stability is maintained, but the area occupied by peripheral circuits increases
Solution Approach 1:
The patent extracts and eliminates unnecessary components from the conventional data latch circuit design. By removing redundant transistors and simplifying the circuit topology to only four essential transistors, the design achieves minimal area occupation while maintaining data stability through the clever utilization of leakage current, thus resolving the contradiction between area reduction and reliability maintenance.
Solution Approach 2:
The patent changes the operational parameters of the transistor, specifically utilizing the leakage current parameter that is typically considered a defect. By adjusting the circuit design to exploit this parameter rather than suppress it, the patent achieves stable data storage with reduced transistor count and smaller area, resolving the contradiction between area reduction and reliability maintenance.
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 data latch circuit significantly reduces the area occupied by the peripheral circuit, thereby minimizing the overall size of the flash memory chip while maintaining data stability and efficiency.
Implementation Method 1
a fourth transistor (Q4) of the second conductivity type, and a control signal input terminal (Vctl) The data holding capability is achieved by utilizing the leakage current of the fourth transistor (Q4).
Data Source
AI summary
A data latch circuit includes a first transistor of a first conductivity type and a second transistor of the first conductivity type, and a third transistor of a second conductivity type and a fourth transistor of the second conductivity type. The third and fourth transistors are controlled to perform a first control operation to store data in the data latch circuit and to perform a second control operation to read the stored data.