a novel chopping-spinning magfet device vincent frick , huy binh nguyen and luc hebrard

Institut d’Electronique du Solide et des Systèmes- Strasbourg (France) -

A Novel Chopping-Spinning MAGFET Device

Vincent FRICK,Huy Binh NGUYEN and Luc HEBRARD

vincent.frick@iness.c-strasbourg.fr

A Novel Chopping-Spinning MAGFET Device

Vincent FRICK,Huy Binh NGUYEN and Luc HEBRARD

vincent.frick@iness.c-strasbourg.fr

A Novel Chopping-Spinning MAGFET Devicevincent.frick@iness.c-strasbourg.fr

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Outline

• Introduction on MAGFET• Novel Device’s Principle• Experimental Results• Conclusions and outlook

14th of December 2010

A Novel Chopping-Spinning MAGFET Devicevincent.frick@iness.c-strasbourg.fr

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MAGFET devicePlan

• Introduction on MAGFET

• Novel Device’s Principle

• Experimental Results

• Conclusions and outlook

14th of December 2010

B

WL

W/2

W/2 I D1 I S 2 I 2I D2 I S 2 I 2I D1= I S /2I D2= I S /2

A Novel Chopping-Spinning MAGFET Devicevincent.frick@iness.c-strasbourg.fr

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Characteristics

• Pros – High sensitivity (optimization possible)– Fully compatible with CMOS

technology– Amplifier input stage

• Cons– Offset– 1/f noise =

poor resolution

Plan

• Introduction on MAGFET

• Novel Device’s Principle

• Experimental Results

• Conclusions and outlook

14th of December 2010

A Novel Chopping-Spinning MAGFET Devicevincent.frick@iness.c-strasbourg.fr

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ImprovementPlan

• Introduction on MAGFET

• Novel Device’s Principle

• Experimental Results

• Conclusions and outlook

14th of December 2010

• Spinning current ?– Only for Hall plates (Hall effect)– Current lines deflection in our case

• Chopper stabilization ?– Impossible to swap the “input” signal

(intrinsic)

Chopping-Spinning !

A Novel Chopping-Spinning MAGFET Devicevincent.frick@iness.c-strasbourg.fr

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Novel Device’s StructurePlan

• Introduction on MAGFET

• Novel Device’s Principle

• Experimental Results

• Conclusions and outlook

14th of December 2010

A Novel Chopping-Spinning MAGFET Devicevincent.frick@iness.c-strasbourg.fr

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Chopping-Spinning PrinciplePlan

• Introduction on MAGFET

• Novel Device’s Principle

• Experimental Results

• Conclusions and outlook

14th of December 2010

I D1 I D1mag I offA I nAI D2 I D2mag I offB I nB

Gate

A B

D C

ID1

ID2

IS

ID1

ID2

IS

ID1ID2

IS

I D1

I D2

I S I D1 I D1mag I offB I nBI D2 I D2mag I offC I nC

I D1 I D1mag I offC I nCI D2 I D2mag I offD I nD

I D1 I D1mag I offD I nDI D2 I D2mag I offA I nA

cteIII DDS 21

III

III

SmagD

SmagD

2/

2/

2

1

A Novel Chopping-Spinning MAGFET Devicevincent.frick@iness.c-strasbourg.fr

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Signal conditioning Plan

• Introduction on MAGFET

• Novel Device’s Principle

• Experimental Results

• Conclusions and outlook

14th of December 2010

IRVout

A Novel Chopping-Spinning MAGFET Devicevincent.frick@iness.c-strasbourg.fr

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Amplifying and Output stagePlan

• Introduction on MAGFET

• Novel Device’s Principle

• Experimental Results

• Conclusions and outlook

14th of December 2010

• Differential stage gain

• Known issues– Limited gain optimization possibilities– Current output: 1/f noise in T-gates

PMAGFET

MAGFET

d

dsds

mv gg

gA

Device geometry

dependency

A Novel Chopping-Spinning MAGFET Devicevincent.frick@iness.c-strasbourg.fr

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Prototype circuitPlan

• Introduction on MAGFET

• Novel Device’s Principle

• Experimental Results

• Conclusions and outlook

14th of December 2010

AMS 0.35µm technologyMAGFET size: 25x25 µm

A Novel Chopping-Spinning MAGFET Devicevincent.frick@iness.c-strasbourg.fr

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Sensitivity and linearityPlan

• Introduction on MAGFET

• Novel Device’s Principle

• Experimental Results

• Conclusions and outlook

14th of December 2010

Sensitivity: up to 4mA/T

gate voltage

A Novel Chopping-Spinning MAGFET Devicevincent.frick@iness.c-strasbourg.fr

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Sensitivity and linearityPlan

• Introduction on MAGFET

• Novel Device’s Principle

• Experimental Results

• Conclusions and outlook

14th of December 2010

-6 -4 -2 0 2 4 61,97

1,98

1,99

2

2,01

Magnetic field (mT)

Sys

tem

's o

utpu

t vo

ltage

(V

)

Linearity: 0.9998 %

A Novel Chopping-Spinning MAGFET Devicevincent.frick@iness.c-strasbourg.fr

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Noise performance and resolution

Plan

• Introduction on MAGFET

• Novel Device’s Principle

• Experimental Results

• Conclusions and outlook

14th of December 2010

A Novel Chopping-Spinning MAGFET Devicevincent.frick@iness.c-strasbourg.fr

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Noise performance and resolution

Plan

• Introduction on MAGFET

• Novel Device’s Principle

• Experimental Results

• Conclusions and outlook

14th of December 2010

Without chopping-Spinning

A Novel Chopping-Spinning MAGFET Devicevincent.frick@iness.c-strasbourg.fr

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Noise performance and resolution

Plan

• Introduction on MAGFET

• Novel Device’s Principle

• Experimental Results

• Conclusions and outlook

14th of December 2010

With chopping-Spinning

56µT resolution

A Novel Chopping-Spinning MAGFET Devicevincent.frick@iness.c-strasbourg.fr

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Conclusions and outlookPlan

• Introduction on MAGFET

• Novel Device’s Principle

• Experimental Results

• Conclusions and outlook

14th of December 2010

• Novel device– Simple MOSFET based geometry– Highly linear– Promising performances

• Improvements– Geometry– Use as active load in differential stage– Larger T-gates: less 1/f noise

A Novel Chopping-Spinning MAGFET Devicevincent.frick@iness.c-strasbourg.fr

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Thank you !

14th of December 2010