Memory Page Buffer Multi-State Sensing Read Speed
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Solution Overview
Problem
Current memory devices face inefficiencies in read and program verify operations, particularly in distinguishing multiple program states, which hinders speed and performance.
Innovation Solution
A memory device and operating method that utilize a page buffer to perform read and program verify operations by applying specific voltages and sensing signals, allowing for the differentiation of multiple program states using a single read or verify voltage through pre-evaluation and post-evaluation operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensing operations are performed to distinguish multiple program states, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent segments the sensing operation into multiple phases (first sensing operation, second sensing operation, third sensing operation) that sequentially evaluate different voltage levels. Each phase distinguishes specific program states by comparing sensed voltages against reference thresholds, enabling multi-state differentiation without requiring multiple complete sensing cycles. This segmentation allows the system to achieve high measurement precision while reducing total operation time compared to traditional multi-voltage sensing approaches.
2Measurement precision
If multiple sensing operations are performed to distinguish multiple program states, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent implements a universal sensing mechanism that can distinguish multiple program states (at least three states) using a single integrated sensing architecture. The page buffer and sensing circuitry perform multiple evaluation functions by sequentially applying different reference voltages and comparing sensed results, eliminating the need for separate dedicated sensing circuits for each program state. This multi-functional approach maintains measurement precision while reducing device complexity compared to having independent sensing paths for each state.
Solution Approach 2:
The patent performs preliminary evaluation operations before the final sensing decision. The first and second sensing operations evaluate intermediate voltage levels and program states, allowing the system to pre-determine which program states are present before performing the final third sensing operation. This preliminary action reduces the complexity of the overall sensing process by breaking down the multi-state differentiation into manageable sequential steps rather than requiring a single complex simultaneous evaluation.
3Measurement precision
If multiple read voltages are applied to distinguish multiple program states, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent employs periodic action by sequentially applying different reference voltages (first reference voltage, second reference voltage, third reference voltage) at different time periods during the read operation. Each voltage application period performs a specific sensing function to distinguish particular program states. This periodic voltage application achieves high measurement precision for multi-state detection while maintaining productivity because the sequential periodic operations are more efficient than simultaneously managing multiple voltage applications or requiring multiple complete read cycles.
Data Source
AI summary
There are provided a memory device and an operating method thereof. The memory device includes: a memory cell; a bit line and a word line, coupled to the memory cell; and a page buffer configured to perform a read operation on the memory cell, wherein the page buffer senses a program state of the memory cell as one of at least three program states by performing a first evaluation operation, a first sensing operation, a second evaluation operation, and a second sensing operation when one read voltage is applied to the word line during the read operation.