Non-Volatile Memory Word-Line Boosting for Fast, Reliable Reads
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Solution Overview
Problem
Existing non-volatile memory technologies face challenges in rapidly boosting the voltage on unselected word lines to a pass voltage during read operations, leading to potential failures in correctly performing read or verification operations.
Innovation Solution
A method involving a first voltage with a steep slope is applied to unselected word lines, followed by stopping this voltage at a predetermined voltage higher than the pass voltage and transitioning to a second voltage at or below the pass voltage to ensure rapid charging without overcharging, utilizing a comparator and drive circuits to control the voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a voltage is supplied to unselected word lines to boost their voltage to pass voltage during read operation, then the read operation can be correctly performed, but it is too slow to boost the voltage of the unselected word lines to the pass voltage due to magnitude or duration of voltage supplied
Solution Approach 1:
The patent applies dynamic voltage boosting by initially supplying a first voltage with a first slope to rapidly increase the voltage on unselected word lines, then switching to a second voltage with a second slope (where the first slope is greater than the second slope) to smoothly charge the word lines to the pass voltage. This dynamic adjustment of voltage characteristics resolves the contradiction by achieving both fast initial boosting and reliable precise charging.
Solution Approach 2:
The patent employs periodic action by dividing the voltage boosting process into two distinct stages: a first period where a first voltage is applied to rapidly boost the word line voltage, and a second period where a second voltage is applied to complete the charging to pass voltage. This staged approach enables both rapid voltage rise and precise control, resolving the speed-reliability contradiction.
2Speed
If a first voltage rising at a first slope is applied to unselected word lines to charge them rapidly, then the voltage can rise quickly to pass voltage, but overcharging may occur if the voltage continues to rise above the pass voltage
Solution Approach 1:
The patent implements feedback control by monitoring the voltage on unselected word lines during the boosting process and switching from the first voltage to the second voltage when the voltage reaches or approaches the pass voltage. This feedback mechanism ensures rapid voltage rise initially while preventing overcharging, thus resolving the contradiction between speed and precision.
Solution Approach 2:
The patent uses dynamic voltage adjustment by transitioning from a first voltage with a steeper slope to a second voltage with a gentler slope when the unselected word line voltage approaches the pass voltage. This dynamic switching enables both rapid initial charging and precise control to avoid overcharging, resolving the speed-precision contradiction.
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
This approach allows for quick voltage rise on unselected word lines to the pass voltage, enhancing the efficiency of read operations and preventing overcharging, thereby improving the reliability and speed of data retrieval in non-volatile memories.
Implementation Method 1
inputting a ramp voltage rising with time, and a boosted drive voltage to the comparator to allow the comparator to output a pulse signal
Implementation Method 2
applying a first voltage rising at a first slope to unselected word lines among a plurality of word lines to charge the unselected word lines to allow a second voltage on the unselected word lines to rise at a second slope
Data Source
AI summary
A method of operating a non-volatile memory including an unselected word line is provided. A first voltage rising at a first slope is applied by a voltage generator to the unselected word line. Outputting the first voltage is stopped by the voltage generator in response to that the first voltage rises to a predetermined voltage, wherein the predetermined voltage is higher than a pass voltage. The pass voltage is outputted by the voltage generator to the unselected word line.