Sense Amplifier Circuit with Multiple Reference Levels for Memory Data Reliability

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Solution Overview

Problem

Semiconductor memory devices face data corruption issues due to variations in threshold voltage of memory cell transistors, leading to malfunction and failure, even with Error Correction Code (ECC) circuits, as they cannot correct errors beyond a certain threshold.

Innovation Solution

A data read-out circuit with a sense amplifier and selector that generates multiple read data using different reference levels, allowing the selector to choose the most reliable output based on error bit detection, thereby improving data reliability and reducing device malfunction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single reference level is used for data reading, then the circuit configuration is simple, but data reliability deteriorates due to bit errors that cannot be corrected by ECC

Engineering Contradiction:

Improvedata reliabilityVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The sense amplifier circuit is divided into multiple independent sense amplifiers (first sense amplifier and second sense amplifier), each using different reference levels to read data from the same memory cell. This segmentation allows multiple read data to be generated in parallel, improving data reliability through diversity while maintaining manageable circuit complexity through modular design

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different reference levels (first reference level and second reference level) are used as varying parameters in the sense amplifier circuits. By changing the reference level parameter, the invention creates multiple read data versions with different error characteristics, allowing the ECC circuit to select the most reliable data version and thereby improve overall data reliability

Inventive Principle:

Principle #35Parameter changes

2Reliability

If multiple sense amplifiers with different reference levels are used, then data reliability is improved, but device complexity increases

Engineering Contradiction:

Improveoutput data reliabilityVSAvoidsense amplifier circuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Multiple sense amplifiers are designed with identical circuit structures that can universally handle the same memory cell, but differentiated by their reference level parameters. This universal design approach allows the circuit to perform multiple reading operations with different reference levels while maintaining structural simplicity and reducing overall device complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The sense amplifier circuit is segmented into multiple independent units (first sense amplifier circuit and second sense amplifier circuit), each capable of independent operation. This segmentation allows the system to generate multiple read data in parallel, improving reliability while keeping each segment's complexity manageable and the overall architecture organized

Inventive Principle:

Principle #1Segmentation

3Reliability

If ECC circuit is used to correct errors, then some error bits can be corrected, but malfunction occurs when error bits exceed the correctable number

Engineering Contradiction:

Improvedata correctnessVSAvoiddata corruption

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention prepares multiple read data versions in advance, each with different error characteristics due to different reference levels. This beforehand cushioning ensures that even if one read data version has excessive errors beyond ECC correction capability, other versions may have fewer errors and can be successfully corrected, preventing system malfunction

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

By changing the reference level parameter across multiple sense amplifiers, the invention creates diversity in error patterns. This parameter variation ensures that not all read data versions will have the same number or type of errors, allowing the ECC circuit to find a correctable version and maintain data correctness even when some versions exceed correction limits

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8091008B2Data read-out circuit in semiconductor memory device and method of data reading in semiconductor memory device

Publication Date: 2012.01.03 RENESAS ELECTRONICS CORP

AI summary

A data read-out circuit is provided with a sense amplifier circuit and a selector. The sense amplifier circuit senses a stored data stored in a memory cell array by using a plurality of reference levels to generate a plurality of read data, respectively. Thus, the sense amplifier circuit outputs the plurality of read data with regard to the stored data. The selector selects a data corresponding to any one of the plurality of read data based on a control signal and outputs the selected data as an output data.