Flash Memory Bad Block Management via Fuse Address Comparison
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Solution Overview
Problem
In flash memory devices, the existing method of using block fuses to disable bad blocks is inefficient due to the large area occupied by fuses and the need for fuses in all memory blocks, which is not practical for effective address control.
Innovation Solution
A flash memory device that stores bad block addresses using a fuse circuit and compares them with input addresses to enable or disable memory blocks, eliminating the need for fuses in each block by using a comparator and address counter to manage bad block information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If block fuses are used in all memory blocks to disable bad blocks, then bad blocks can be effectively disabled, but the area occupied by fuse circuits becomes large
Solution Approach 1:
The patent merges the bad block disabling function from individual block-level fuses into a centralized comparator circuit that receives block addresses and compares them against stored bad block addresses. This consolidation eliminates the need for separate fuse circuits in each block, significantly reducing total fuse circuit area while maintaining the ability to disable bad blocks through address-based control.
Solution Approach 2:
The patent introduces a comparator circuit as an intermediary between the block address input and the block enable signal. This comparator acts as a mediator that determines whether to enable or disable a block based on address comparison, replacing the direct fuse-based disabling mechanism and allowing for more efficient use of fuse circuits.
2Reliability
If fuses are placed in all memory blocks to disable bad blocks, then bad blocks can be disabled, but the device complexity increases
Solution Approach 1:
The patent consolidates the bad block disabling functionality into a single centralized comparator unit rather than distributing fuse circuits across all blocks. This merging approach simplifies the overall device architecture by reducing the number of discrete fuse components and their interconnections, thereby lowering device complexity while preserving bad block management capability.
Solution Approach 2:
The comparator circuit serves multiple functions: it compares block addresses, identifies bad blocks, and controls block enabling/disabling. This multi-functional approach replaces the simple binary fuse mechanism with a more versatile component that handles address-based control, reducing the need for additional dedicated circuits and simplifying the overall system.
Data Source
AI summary
A bad block address of a flash memory device is stored through a fuse circuit and then compared with an input address in order to disable bad blocks. The flash memory device includes a bad block information unit for storing an address of a bad block, a comparator for comparing an input address including a memory block address and the address of the bad block stored in the bad block information unit, and for outputting a first control signal according to the comparison result, and an address counter for outputting a second control signal to enable or disable a memory block corresponding to the memory block address in response to the first control signal.