Non-Volatile Memory Read Current Measurement Isolation
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Solution Overview
Problem
Conventional non-volatile memory devices face challenges in accurately measuring the read current due to the inclusion of current components from standby and other states in the average read current measurement, making it difficult to isolate the cell current during read operations.
Innovation Solution
The non-volatile memory device measures the current generated during a read operation by latching the sense amplifier's enable time and mandatorily turning off the column switching unit, allowing for the subtraction of current from external circuits to isolate the cell current, using a method that involves latch units and column controllers to control signal activation and deactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional read current measurement method is used, then read operation can be performed, but measurement precision deteriorates due to inclusion of standby and other current components
Solution Approach 1:
The patent segments the current measurement process into distinct phases: first measuring total current during read operation, then measuring standby current separately, and finally subtracting the standby component from the total to obtain pure read current. This segmentation allows precise measurement by isolating the target current component from interfering components.
Solution Approach 2:
The patent performs preliminary measurement of standby current before calculating the actual read current. By measuring the standby current component first (when column switching unit is off) and then subtracting it from the total current measured during read operation, the method prepares necessary data in advance to achieve precise read current measurement.
2Measurement precision
If repeated read operations are performed for measurement, then measurement data can be obtained, but productivity deteriorates due to time consumption
Solution Approach 1:
The patent performs preliminary measurement of standby current in advance, storing it for later subtraction from total current measurements. This preliminary action eliminates the need for repeated read operations to isolate cell current, as the standby component is already characterized and can be subtracted directly, significantly improving measurement efficiency while maintaining precision.
Solution Approach 2:
The measurement system uses itself to characterize its own parasitic currents by measuring standby current through the same measurement path and components. This self-service approach allows the system to automatically compensate for measurement path contributions without requiring external calibration or repeated operational measurements.
3Measurement precision
If column switching unit remains on during measurement, then read operation continues, but measurement precision deteriorates due to inclusion of external circuit currents
Solution Approach 1:
The patent segments the measurement process into two distinct temporal phases: first measuring total current with column switching unit on, then measuring standby current with column switching unit off. This temporal segmentation allows isolation of cell current from external circuit currents by subtracting the second measurement from the first, achieving precise cell current measurement.
Solution Approach 2:
The measurement method employs periodic alternation between two states: read operation state (column switching on) and standby measurement state (column switching off). By periodically switching between these states and comparing measurements, the system isolates the cell current component from external circuit contributions, achieving precise measurement without requiring prolonged single-state operation.
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 enables accurate measurement of the current flowing only in the unit cell during read operations, eliminating the need for repeated read operations and improving measurement precision by isolating the cell current from other circuit currents.
Implementation Method 1
If a voltage and a current are applied to the top electrode 1 and the bottom electrode 3, a current signal is provided to the PCM layer 2, and a temperature of the PCM layer rises, such that an electrical conductive status of the PCM layer 2 changes depending on resistance variation.
Implementation Method 2
If heat is applied to the GST, it changes to a crystalline phase or an amorphous phase, thereby storing data in the memory cell.
Data Source
AI summary
A non-volatile memory device for measuring a read current of a unit cell is provided. The non-volatile memory device includes a unit cell configured to read or write data, a column switching unit configured to select the unit cell in response to a column selection signal, a sense amplifier controlled by a sense-amplifier enable signal, configured to sense and amplify data that is received from the unit cell through the column switching unit, a first latch unit configured to latch the sense-amplifier enable signal for a predetermined time when a test code signal received from an external part is activated, a column controller configured to output a latch control signal in response to a combination of a column switch-off signal and a column control signal, and a second latch unit configured to control whether or not the column selection signal is latched in response to an activation state of the latch control signal.