Memory Cell Read Mechanism Using Clock Pulse Counts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing memory devices face inefficiencies in reading memory cell states due to lengthy settling times and inaccurate threshold voltage readings caused by rapid discharge of electrical current and undesired voltage biases, especially when sensing multiple threshold voltages in flash memory devices.
Innovation Solution
The use of clock pulse counts to trigger sense amplifiers, allowing for fixed wordline voltages and reduced settling times, and selecting different pulse counts and clock periods to improve resolution and accuracy of memory cell programmed states, thereby eliminating the need for extensive voltage ramping and reducing RC delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional voltage ramping methods are used to sense memory cell threshold voltages, then measurement precision can be achieved, but reading speed and productivity are reduced due to lengthy settling times
Solution Approach 1:
The patent changes the sensing parameter from voltage-based (requiring voltage ramping and settling) to time-based (using fixed clock periods). By measuring the time required for current to discharge through the memory cell during a fixed clock period, the system eliminates voltage settling time dependencies and achieves parallel sensing of multiple cells without requiring lengthy voltage ramping sequences.
Solution Approach 2:
The patent substitutes the voltage-ramping mechanical process with a time-based measurement approach using clock pulses. Instead of dynamically adjusting voltages and waiting for settling, the system uses fixed time intervals (clock periods) to capture discharge characteristics, replacing complex voltage control mechanisms with simpler timing-based operations.
2Measurement precision
If voltage ramping is used to sense multiple threshold voltages, then measurement precision is maintained, but device complexity and RC delays increase
Solution Approach 1:
The patent extracts the voltage ramping and control complexity from the sensing operation. By using fixed clock periods to measure discharge times, the system separates the sensing function from complex voltage control, allowing multiple threshold voltages to be sensed simultaneously without requiring coordinated voltage ramping sequences for each cell.
Solution Approach 2:
The patent segments the sensing process into independent time-based measurements for each memory cell. Each cell's threshold voltage is determined by measuring its individual discharge time constant during a fixed clock period, allowing parallel processing of multiple cells without inter-dependent voltage control complexity.
3Measurement precision
If traditional sensing methods are used, then threshold voltage can be read, but loss of time occurs due to lengthy settling times
Solution Approach 1:
The patent performs preliminary action by establishing a fixed clock period before measurement begins. This pre-defined time reference eliminates the need for post-measurement settling waits, as the measurement itself is conducted within the fixed clock period. The system prepares timing references in advance rather than waiting for voltage settling during the measurement process.
Solution Approach 2:
The patent skips the lengthy voltage settling process entirely by using time-based measurement. Instead of waiting for voltages to stabilize before reading, the system measures discharge characteristics within fixed time intervals, effectively rushing through the sensing operation without being constrained by voltage settling time requirements.
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 enhances the speed and accuracy of reading memory cell states by maintaining fixed wordline voltages, decreasing settling times, and allowing for quicker and more precise determination of threshold voltages across multiple memory cells.
Implementation Method 1
the sense amplifiers can be used to latch logical values corresponding to the electrical current flowing through the memory cells
Data Source
AI summary
A disclosed example determines programmed states of a plurality of memory cells based on a counter reaching a trigger count value, the trigger count value selected from a plurality of different trigger count values based on a characteristic of the memory cells; determines, based on the programmed states, first ones of the memory cells that do not satisfy a target threshold voltage; and performs the programming pass on the first ones of the memory cells.