Negative Potential Discharge Circuit for NOR Flash Memory
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Solution Overview
Problem
Increased parasitic capacitance in NOR flash memory arrays affects the application and discharge of erase voltage during erase operations, making it difficult to maintain a constant discharge rate due to changes in externally applied power supply voltage.
Innovation Solution
A negative potential discharge circuit with an internal voltage generating circuit and discharge unit, which includes a level shifter, inverter, PMOS and NMOS transistors, and an output terminal, generates a regulated output voltage to ensure constant discharge rate by boosting the power supply voltage and limiting it to a desired level, thereby maintaining a stable voltage for discharging accumulated charges on a word line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the memory array size is increased to increase memory capacity, then the storage capacity is improved, but the parasitic capacitance increases making it difficult to maintain constant discharge rate
Solution Approach 1:
The patent changes the operating parameters by introducing an internal reference voltage that is independent of the external power supply voltage. The discharge circuit uses this reference voltage to regulate the discharge rate, thereby maintaining consistent discharge characteristics even as the memory array size and parasitic capacitance increase.
2Adaptability or versatility
If external power supply voltage varies, then the circuit operates under different voltage conditions, but the discharge rate becomes inconsistent
Solution Approach 1:
The patent introduces an internal reference voltage as an intermediary between the external power supply and the discharge circuit. This reference voltage acts as a mediator that decouples the discharge circuit from external voltage variations, ensuring consistent discharge rate regardless of the external power supply conditions.
Solution Approach 2:
The discharge circuit uses the internal reference voltage to establish a stable operating point, changing the parameter basis from external power supply voltage to internal reference voltage. This parameter change enables the circuit to maintain consistent discharge characteristics across different external voltage conditions.
3Device complexity
If simple discharge circuit is used, then the device complexity is reduced, but the discharge time increases
Solution Approach 1:
The discharge circuit performs self-regulation by using the internal reference voltage to automatically control the discharge rate. The circuit monitors its own operating conditions and adjusts the discharge current accordingly, eliminating the need for complex external control mechanisms while achieving fast and consistent discharge.
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 allows for consistent and efficient discharge of negative potential at a constant rate, independent of changes in the external power supply voltage, improving the discharge characteristics and reducing discharge time during erase operations in NOR flash memory.
Implementation Method 1
an internal voltage generating circuit configured to generate a regulated output voltage based on a power supply voltage
Implementation Method 2
a discharge unit configured to discharge a negative potential using the regulated output voltage
Implementation Method 3
The discharge unit may include a level shifter configured to shift a level of a first discharge timing signal by dividing the regulated output voltage
Data Source
AI summary
A negative potential discharge circuit may include an internal voltage generating circuit and/or a discharge unit. The internal voltage generating circuit may be configured to generate a regulated output voltage based on a power supply voltage. The discharge unit may be configured to discharge a negative potential using the regulated output voltage. A method of discharging a negative potential may include generating a regulated output voltage based on a power supply voltage, and/or discharging a negative potential using the regulated output voltage.