Source Line Floating Circuit for Memory Read Reliability
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Solution Overview
Problem
In semiconductor memory devices, leakage currents from unselected memory cells can degrade the reliability of read operations by affecting bit line voltage, leading to inaccurate data retrieval.
Innovation Solution
A source line floating circuit is introduced, which disconnects unselected source lines from the source voltage during a read operation, reducing leakage currents and enhancing the reliability of data reading by selectively floating the source lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all source lines are connected to source voltage during read operation, then all memory cells can be accessed, but leakage currents from unselected memory cells degrade read reliability
Solution Approach 1:
The source line control is segmented into individual selectable lines. Each source line can be independently connected to or disconnected from the source voltage through switching elements controlled by decoded row address signals. This segmentation allows only the selected source line to remain connected while unselected lines are disconnected, eliminating leakage currents from unselected memory cells while maintaining access to the intended memory cell.
2Ease of operation
If unselected source lines remain connected to source voltage, then circuit operation is simple, but bit line voltage is affected by leakage currents
Solution Approach 1:
Switching elements are introduced as intermediary components between the source voltage and each source line. These switching elements act as mediators that can selectively connect or disconnect the source voltage from specific source lines based on the selected memory cell. This intermediary mechanism maintains circuit simplicity by using standard switching components while achieving precise control over which source lines receive voltage, thereby ensuring accurate bit line voltage measurement without interference from leakage currents.
Data Source
AI summary
A source line floating circuit includes a plurality of floating units. The floating units directly receive decoded row address signals or voltages of word lines as floating control signals, respectively. The decoded row address signals are activated selectively in response to a row address signal. The floating units control electrical connections between source lines and a source voltage in response to the floating control signals in a read operation. Related devices and methods are also described.