Gain-Cell Storage Circuit With Self-Refresh Read-Write Operation

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Solution Overview

Problem

Existing computing-in-memory (CIM) systems face challenges in maintaining data integrity due to leakage currents, requiring complex sense amplifiers that occupy large areas and prevent simultaneous read and write operations.

Innovation Solution

A storage circuit comprising a gain-cell, self-refresh unit, and latch circuit that allows for simultaneous read and write operations without occupying large areas, utilizing parasitic capacitors for storage and a self-refresh mechanism to maintain data integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If complex sense amplifiers are used to maintain data integrity, then data integrity is improved, but area overhead increases and simultaneous read-write operations cannot be performed

Engineering Contradiction:

Improvedata integrityVSAvoidarea overhead

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent extracts the data maintenance function from the complex sense amplifier and implements it through a simpler self-refresh unit that operates independently. This self-refresh unit only performs refresh operations on selected rows, separating the refresh function from the read function, thereby reducing area overhead while maintaining data integrity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The storage circuit is segmented into distinct functional units: gain-cells for storage, self-refresh units for maintenance, and latch circuits for reading. This segmentation allows simultaneous operation of different units - self-refresh units can maintain data integrity while latch circuits perform read operations, resolving the contradiction between reliability and area efficiency.

Inventive Principle:

Principle #1Segmentation

2Reliability

If complex sense amplifiers are used to maintain data integrity, then data integrity is improved, but simultaneous read and write operations cannot be performed

Engineering Contradiction:

Improvedata integrityVSAvoidsimultaneous read-write operation capability

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent divides the storage circuit into spatially separated gain-cells and functional units (self-refresh units and latch circuits). This segmentation enables independent operation - self-refresh units can maintain data in selected rows while latch circuits simultaneously perform read operations on other rows, achieving both data integrity and simultaneous read-write capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The self-refresh unit dynamically selects which rows to refresh based on operational needs, allowing flexible scheduling of refresh operations. This dynamic operation enables simultaneous read and write operations by time-multiplexing or space-multiplexing different operations across different circuit units, thereby improving productivity while maintaining reliability.

Inventive Principle:

Principle #15Dynamics

3Area of stationary object

If traditional storage circuits are used, then area overhead is reduced, but data integrity cannot be maintained without complex sense amplifiers

Engineering Contradiction:

Improvearea overheadVSAvoiddata integrity

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The self-refresh unit enables the storage circuit to maintain data integrity autonomously without requiring complex external sense amplifiers. The unit automatically detects and corrects leakage currents in the capacitors of selected rows, providing self-service data maintenance that reduces area overhead while ensuring reliability.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent changes the operational parameters by using lower-power, simpler refresh transistors instead of high-power sense amplifiers. The self-refresh unit operates with reduced current requirements, allowing data integrity maintenance with minimal area overhead. The circuit uses controlled parameter changes in transistor operation to achieve efficient data maintenance without complex amplification.

Inventive Principle:

Principle #35Parameter changes

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

Enables high-speed computations by allowing simultaneous read and write operations while reducing area overhead, thus enhancing the performance of CIM systems.

Implementation Method 1

Each of the plurality of gain-cells in the storage array includes a capacitor that is configured to store a respective one of the data

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

maintaining data integrity due to leakage currents

Methodology Applied

Scientific EffectLeakage current detection:

Data Source

PatentUS20250239289A1Storage circuit, self-refresh unit and memory array

Publication Date: 2025.07.24 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

In this disclosure, a storage circuit is provided. The storage circuit includes a gain-cell, a self-refresh unit, and a latch circuit. The gain-cell is configured to store first data in a gate of a storage transistor. The self-refresh unit is configured to read the first data from the gain-cell and write the first data back to the gain-cell. The latch circuit is configured to read the first data from the self-refresh unit and latch the first data.