Independent Voltage and TCO Control in Flash Memory
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Solution Overview
Problem
Conventional systems fail to independently control the voltage level and temperature coefficient (TCO) in flash memory devices, leading to inaccurate data reading due to mismatched thermal variations, and inefficient trimming of TCO values during testing.
Innovation Solution
A system comprising a temperature-dependent voltage generator and a temperature-independent voltage generator, controlled by multipliers, is used to produce a voltage for read and program-verify operations, with an amplifier combining their outputs to apply voltages that match the intrinsic TCO of memory cells, and a testing module for trimming TCO values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional voltage generation is used, then the system is simple, but the voltage and temperature coefficient cannot be independently controlled, leading to mismatched thermal variations
Solution Approach 1:
The voltage generation system is segmented into two independent components: a temperature-dependent voltage generator and a temperature-independent voltage generator. Each generator handles a specific aspect of voltage control, allowing independent adjustment of voltage level and temperature coefficient through separate multipliers (K1 and K2). This segmentation enables precise control of thermal variations without requiring complete system redesign.
Solution Approach 2:
The system employs dynamic control elements including temperature-dependent and temperature-independent voltage generators that can adapt their output based on operating conditions. The multipliers K1 and K2 provide dynamic adjustment capability, allowing the system to optimize voltage and temperature coefficient independently for different operating scenarios, enhancing adaptability while maintaining manageable complexity.
2Measurement precision
If predetermined voltages are applied without independent TCO control, then the system operation is simple, but data reading accuracy deteriorates due to mismatched thermal variations
Solution Approach 1:
The system incorporates feedback mechanisms through temperature sensing and adaptive voltage adjustment. The temperature-dependent voltage generator responds to temperature changes by adjusting its output accordingly, while the temperature-independent generator provides a stable reference. This feedback-based approach ensures that the combined voltage output maintains accurate alignment with memory cell threshold voltages across varying temperatures, significantly improving data reading accuracy.
Solution Approach 2:
The system dynamically changes voltage parameters by independently adjusting the voltage level (through multiplier K2) and temperature coefficient (through multiplier K1). This parameter control allows the system to optimize voltage characteristics for different operating conditions, ensuring high measurement precision in data reading while managing the complexity through systematic parameter adjustment rather than structural complexity.
3Reliability
If TCO trimming is performed during testing, then the TCO values can be optimized, but the testing process becomes more time-consuming
Solution Approach 1:
The system performs TCO trimming during the manufacturing testing phase, establishing optimal K1 and K2 values before the product reaches the customer. This preliminary action ensures that the voltage and temperature coefficient are pre-optimized for each device, improving reliability without requiring time-consuming adjustments during field operation. The one-time trimming during manufacturing balances testing time investment with long-term operational reliability.
Data Source
AI summary
Method and system for controlling voltage and its temperature co-efficient in a non-volatile memory device having a plurality of programmable memory cells is provided. The system includes a temperature-dependent voltage generator for generating an output that is controlled independently by a first multiplier; a temperature-independent voltage generator having a constant output, wherein the constant output is controlled by a second multiplier; and an amplifier that receives the constant output of the temperature-independent voltage generator and the output of temperature-dependent voltage generator to generate a voltage that is applied to a memory cell for a read, and program-verify operation; wherein the temperature co-efficient and voltage applied to memory cells is controlled independently so that intrinsic temperature coefficient of the memory cell is substantially similar to temperature coefficient of the applied voltage.