Memory Charge Recycling Arrangement for Read Energy Reduction

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Solution Overview

Problem

Memory devices consume a significant amount of energy during read operations due to the precharge mode, where a large portion of the charge is wasted during the discharge phase, and the existing three-mode read operation structure is inefficient in terms of energy usage and time.

Innovation Solution

The implementation of a two-phase precharge and reuse mechanism, where charges are recovered and reused from capacitors onto branched lines before pre-filling, and charges are recovered from bit and bit_bar lines before drainage, reducing the energy required for the read operation and shortening the duration of the pre-fill and drainage phases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a three-mode read operation structure (precharge, evaluation, discharge) is used, then the memory device can complete read operations, but a large portion of charge is wasted during the discharge phase resulting in high energy consumption

Engineering Contradiction:

Improveenergy consumptionVSAvoidread operation efficiency

Core Design Contradiction:

Loss of energyVSProductivity

Solution Approach 1:

The patent recovers charge from the bit line and bit_bar line during the discharge phase by connecting them to capacitors, preventing charge waste. The recovered charge is then reused during the precharge phase, transforming the previously wasteful discharge process into a charge recovery mechanism that reduces overall energy consumption.

Inventive Principle:

Principle #34Discarding and recovering

Solution Approach 2:

The patent extends the read operation to include additional phases (pre-boost, recovery, reuse) that continue the charge utilization process. The pre-boost phase partially charges lines before the main read operation, and the recovery phase captures remaining charge, creating continuous charge utilization rather than discrete three-mode operation.

Inventive Principle:

Principle #20Continuity of useful action

2Use of energy by stationary object

If charge is completely drained to ground during the discharge phase, then the read operation can be simplified, but the energy required for the read operation increases significantly

Engineering Contradiction:

Improveenergy required for read operationVSAvoidcharge wasted during discharge

Core Design Contradiction:

Use of energy by stationary objectVSLoss of energy

Solution Approach 1:

Instead of completely draining charge to ground, the patent recovers charge by connecting bit lines to capacitors during the discharge phase. This recovered charge is then reused during precharge, significantly reducing the energy required for subsequent read operations.

Inventive Principle:

Principle #34Discarding and recovering

Solution Approach 2:

The patent introduces a pre-boost phase that performs preliminary charging of bit lines and bit_bar lines before the main read operation. This preliminary action reduces the charge that needs to be supplied during the actual read operation, lowering overall energy consumption.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the read operation includes complete precharge and discharge cycles, then the memory device ensures proper charge states, but the operational time increases

Engineering Contradiction:

Improvecharge state accuracyVSAvoidduration of pre-fill and drainage phases

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies partial precharging through the pre-boost phase, where only a portion of the required charge is supplied before the main read operation. This partial action is sufficient to reduce the burden on the main operation, shortening the total time while maintaining reliability.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

By recovering charge during the discharge phase and reusing it during precharge, the patent reduces the total charge transfer time. The recovery phase captures remaining charge that would otherwise be wasted, accelerating the overall operation while ensuring proper charge states.

Inventive Principle:

Principle #34Discarding and recovering

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach reduces energy consumption and operational time by minimizing the charge drained to ground and the charge provided by the sense amplifier, making the read operation more efficient and reducing energy waste.

Implementation Method 1

a capacitor connected between the first bit line and the first branched line; a second capacitor connected between the second bit line and the second branched line

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

the sense amplifier is configured to make a second evaluation of a stored value in a second memory cell relative to the reference charge

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS20230178120A1Memory device with charge-recycling arrangement and method of operating the same

Publication Date: 2023.06.08 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method (for recycling charge from a first bit line of a memory device to a second bit line of the memory device) includes: before pre-filling the second bit line, momentarily closing switches to transfer a first charge from the first bit line which is involved in a first read operation to the second bit line which is involved subsequently in a second read operation; and each of the first bit line and the second bit line being served by a same sense amplifier.