Phase-changeable Memory Bitline Sensing Margin via High Voltage Pump
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Phase-changeable memory devices using diodes as selection elements face reduced sensing margins during read operations due to threshold voltage limitations, which can degrade read operation performance when the power source voltage decreases below a certain level.
Innovation Solution
A phase-changeable memory device and read method that utilize a voltage pump to generate a high voltage, improving sensing margins by charging bitlines to a high voltage in addition to the power source voltage, and using a sense amplifier to detect voltage levels with this high voltage, thereby enhancing read operation stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a diode is used as a selection element in a phase-changeable memory device, then the device can be manufactured with simple processes, but the sensing margin is reduced during read operations due to threshold voltage limitations
Solution Approach 1:
The patent changes the voltage parameter by introducing a high voltage pump circuit that generates a high voltage (VPH) greater than the power source voltage (VCC). This voltage parameter change allows the bitline to be charged to a higher level, thereby increasing the sensing margin during read operations while maintaining the simple diode-based selection element structure
Solution Approach 2:
The patent introduces a high voltage pump circuit as an intermediary component between the power source and the bitline. This intermediary circuit generates the high voltage needed to overcome the diode's threshold voltage limitation, enabling sufficient sensing margin without changing the fundamental diode selection element design
2Use of energy by moving object
If the power source voltage decreases below a certain level, then energy consumption is reduced, but read operation performance degrades due to insufficient sensing margin
Solution Approach 1:
The patent makes the voltage supply dynamic by using a pump circuit that can operate in different modes. The high voltage pump activates only when needed for read operations, allowing the system to adapt the voltage level based on operational requirements. This enables low power consumption during normal operation while providing high voltage during read operations to maintain performance
Solution Approach 2:
The patent dynamically changes the voltage parameter supplied to the bitline based on operational mode. During read operations, the high voltage pump raises the bitline voltage to VPH to ensure sufficient sensing margin, while during write operations or idle states, the system operates at the lower power source voltage VCC, thus optimizing both performance and power consumption
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 solution ensures a stable read operation with improved sensing margins, reducing the capacitive burden on the high voltage circuit during precharging and maintaining sufficient voltage differences between reset and set states, even when the power source voltage drops below 1.5V.
Implementation Method 1
a voltage pump to generate a high voltage, improving sensing margins by charging bitlines to a high voltage
Implementation Method 2
The physical state of a phase-changeable material can take either a generally crystalline or generally amorphous state
Implementation Method 3
The memory element 11 contains a phage-changeable material, such as Ge—Sb—Te (GST), that can vary in resistance based on its physical state
Implementation Method 4
When a voltage difference between the anode and cathode of the selection element 22 (diode D) becomes higher than the diode's threshold, the selection element 22 is turned on to supply a current
Data Source
AI summary
Disclosed is a phase-changeable memory device and a related method of reading data. The memory device is comprised of memory cells, a high voltage circuit, a precharging circuit, a bias circuit, and a sense amplifier. Each memory cell includes a phase-changeable material and a diode connected to a bitline. The high voltage circuit provides a high voltage from a power source. The precharging circuit raises the bitline up to the high voltage after charging the bitline up to the power source voltage. The bias circuit supplies a read current to the bitline by means of the high voltage. The sense amplifier compares a voltage of the bitline with a reference voltage by means of the high voltage, and reads data from the memory cell. The memory device is able to reduce the burden on the high voltage circuit during the precharging operation, thus assuring a sufficient sensing margin during the sensing operation.