Temperature Compensated Reference Currents for Phase Change Memory Sensing

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Solution Overview

Problem

Current semiconductor memory devices face challenges in accurately sensing multilevel phase change memory cells due to temperature dependence of resistance, which affects the accuracy of data states and requires complex circuitry for temperature compensation.

Innovation Solution

The method involves generating temperature-compensated reference currents by summing initial currents, which are adjusted based on temperature changes to ensure accurate sensing operations across varying temperatures, reducing the complexity of circuitry and power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If temperature compensation circuitry is added to accurately sense multilevel phase change memory cells, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improveaccuracy of data state determinationVSAvoidcomplexity of circuitry

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent changes the parameter of reference current by providing multiple initial reference currents with different magnitudes that are selectively activated based on temperature. Instead of using a single complex temperature compensation circuit, the system selects appropriate reference currents from a set of predefined currents, thereby achieving temperature compensation while maintaining simpler circuitry.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If temperature compensation circuitry is added to accurately sense multilevel phase change memory cells, then measurement precision is improved, but power consumption increases

Engineering Contradiction:

Improveaccuracy of data state determinationVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent changes the parameter of reference current magnitude based on temperature conditions. By providing multiple initial reference currents with different magnitudes and selectively enabling them based on temperature, the system achieves accurate temperature-compensated sensing without continuously powering complex compensation circuitry, thereby reducing overall power consumption.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If multiple initial reference currents with different magnitudes are provided, then adaptability to temperature variations is improved, but device complexity increases

Engineering Contradiction:

Improveaccuracy across varying temperaturesVSAvoidcomplexity of circuitry

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements dynamic adaptation to temperature variations by selectively activating different initial reference currents based on temperature conditions. The system dynamically adjusts which reference current is used rather than maintaining a fixed complex compensation circuit, achieving adaptability through selective activation of predefined current sources.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8760939B2Memory sensing using temperature compensated initial currents

Publication Date: 2014.06.24 OVONYX MEMORY TECHNOLOGY LLC

AI summary

The present disclosure includes devices, methods, and systems for sensing memory, such as resistance variable memory, among other types of memory. One or more embodiments can include a method for generating currents to be used in sensing a memory cell, the method including providing a number of initial currents, and generating a number of reference currents by summing particular combinations of the initial currents.