Boost Voltage Generating Circuit for Memory Programming
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Solution Overview
Problem
Conventional boost voltage generating circuits for semiconductor memory devices, such as flash memory devices, fail to maintain a constant source line voltage during programming operations due to variations in the number of memory cells being programmed, leading to inefficiencies and potential programming failures.
Innovation Solution
A boost voltage generating circuit that includes a voltage comparator, a voltage generator, and a boost voltage controller with a resistor network that adjusts current flow based on the number of memory cells to be programmed, ensuring a stable boost voltage is maintained across the source line by varying the resistance and current distribution through current mirrors and controllers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional boost voltage generating circuit is used with fixed resistance values, then the circuit structure is simple, but the source line voltage cannot be maintained constant when the number of memory cells to be programmed varies
Solution Approach 1:
The patent applies dynamics by making the resistance values variable rather than fixed. The boost voltage controller dynamically adjusts the resistance values of resistors Rta and Rt based on the number of memory cells to be programmed, allowing the source line voltage to remain constant despite changes in programming conditions. This dynamic adjustment resolves the contradiction between voltage stability and circuit simplicity.
Solution Approach 2:
The patent changes the parameter of resistance values from fixed to variable. By controlling the resistance values of resistors Rta and Rt according to the number of memory cells being programmed, the system maintains constant source line voltage. This parameter change enables the circuit to adapt to different programming scenarios without increasing overall structural complexity.
2Reliability
If the boost voltage is increased to compensate for voltage drops in programming mode, then the source line voltage can be maintained, but the boost voltage may exceed the maximum allowable voltage for memory cells
Solution Approach 1:
The patent uses dynamics by making the boost voltage adjustable rather than fixed. The boost voltage controller dynamically sets the boost voltage level based on the number of memory cells to be programmed, ensuring the voltage remains within safe limits while still compensating for drops. This prevents excessive voltage from damaging memory cells while maintaining source line voltage stability.
Solution Approach 2:
The patent changes the boost voltage parameter from a fixed high value to a variable value that adapts to programming conditions. By controlling the boost voltage according to the number of memory cells being programmed, the system avoids applying excessive voltage that could harm memory cells, while still maintaining adequate source line voltage for successful programming.
3Productivity
If a fixed boost voltage is applied during programming operations, then the circuit operation is simple, but programming failures occur due to voltage drops when multiple memory cells are programmed
Solution Approach 1:
The patent applies dynamics by making the boost voltage adjustable rather than fixed. The boost voltage controller dynamically adapts the boost voltage level based on the number of memory cells to be programmed, ensuring sufficient voltage headroom for successful programming. This dynamic adjustment prevents programming failures caused by voltage drops while maintaining simple circuit operation.
Solution Approach 2:
The patent changes the boost voltage parameter from fixed to variable, matching it to the programming workload. When more memory cells are programmed, the boost voltage is increased to compensate for voltage drops; when fewer cells are programmed, the voltage is reduced to avoid excess. This parameter adaptation ensures high programming success rates without complicating the circuit operation.
Data Source
AI summary
A boost voltage generating circuit and method thereof. The example boost voltage generating circuit may include a voltage comparator comparing an input voltage and a reference voltage and generating a control signal based on a result of the voltage comparison, the input voltage based on a feedback boost voltage, a voltage generator generating a boost voltage in response to the control signal and a boost voltage controller including a first resistor with a first end connected to the boost voltage and a second end connected to the voltage comparator, the boost voltage controller controlling a level of current flowing through the first resistor based on one of a number of memory cells to be programmed and a number of cell groups including at least one memory cell to be programmed. The example method may include maintaining a source line voltage for a memory device at a substantially constant voltage level by scaling a boost voltage through control of a level of current flowing through a resistor coupled between a voltage comparator and the boost voltage based on one of a number of memory cells to be programmed in a memory operation and a number of cell groups including at least one memory cell to be programmed in a memory operation.