Current Mirror Circuit with Compensation for Neuromorphic Linearity

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Solution Overview

Problem

Current mirror circuits used in neuromorphic devices suffer from reduced linearity as the voltage of the input node increases, making them unsuitable for hardware implementation of spiking neural networks due to the discrepancy between ideal and actual currents.

Innovation Solution

A current mirror circuit with a compensation circuit connected in parallel to the second switching element, which includes a third switching element to compensate for the difference between ideal and actual currents, maintaining linearity even as the input voltage increases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a general current mirror circuit is used, then the circuit structure is simple, but linearity is reduced as input voltage increases

Engineering Contradiction:

Improvecircuit structureVSAvoidlinearity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The current mirror circuit is divided into multiple independent current mirror units, each handling a specific voltage range. This segmentation allows each unit to operate within its optimal linear range while collectively covering a broader voltage range with maintained linearity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The circuit dynamically switches between different current mirror units based on the input voltage level. This dynamic operation ensures that the circuit always operates in the most appropriate mode for the current conditions, maintaining linearity across varying voltage ranges.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If the voltage of the input node increases, then the power supply voltage range is extended, but the current accuracy deteriorates

Engineering Contradiction:

Improvevoltage rangeVSAvoidcurrent accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The voltage range is segmented into multiple intervals, with each current mirror unit responsible for a specific interval. This ensures that current accuracy is maintained within each segment while the overall circuit adapts to a wider voltage range through unit switching.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The circuit changes operational parameters by switching between different current mirror units with optimized characteristics for different voltage ranges. This parameter change strategy maintains current accuracy across the extended voltage range.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If a compensation circuit is added, then linearity is improved, but device complexity increases

Engineering Contradiction:

ImprovelinearityVSAvoidcircuit structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Instead of adding a single complex compensation circuit, the solution segments the current mirror into multiple simpler units, each with inherent linearity optimization. This approach achieves linearity improvement while keeping individual unit complexity manageable.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS20230135734A1Current mirror circuit and neuromorphic device including same

Publication Date: 2023.05.04 SEOUL NATIONAL UNIVERSITY R&DB FOUNDATION

AI summary

Provided is a current mirror circuit and a neuromorphic device including the current mirror circuit and provides a current mirror circuit that causes an ideal current to flow through the current mirror circuit by using a compensation circuit, and a neuromorphic device including the current mirror circuit.