Battery lifetime modeling for a 2.45GHz cochlear implant application - - PowerPoint PPT Presentation

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Battery lifetime modeling for a 2.45GHz cochlear implant application - - PowerPoint PPT Presentation

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Behavioral Modeling and System conference September 23-24, 2010 3.1 10:00 -10:30 AM Battery lifetime modeling for a 2.45GHz cochlear implant application Yannick Vaiarello Gilles Jacquemod William Tatinian LEAT / Neurelec LEAT UMR UNS

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Battery lifetime modeling for a 2.45GHz cochlear implant application

William Tatinian LEAT UMR UNS CNRS 6071 (+33) 492 94 28 51 william.tatinian@unice.fr Yannick Vaiarello LEAT / Neurelec (+33) 492 94 28 81 yvaiarello@neurelec.com Gilles Jacquemod LEAT UMR UNS CNRS 6071 (+33) 492 38 85 00 gilles.jacquemod@unice.fr

Behavioral Modeling and System conference September 23-24, 2010 – 3.1 – 10:00 -10:30 AM

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Outlines

 Introduction  Communication for cochlear implant  Modeling

 Heterogeneous Simulation Framework  Channel and Antenna Modeling and

simulation

 Transmitter Modeling

 Implementation and Simulation Results  Conclusion

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BMAS 2010 - Session 3.1 - Yannick VAIARELLO

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Introduction

 Severe to Profound Deafness  Current cochlear implant: inductive system  Visible and unattractive

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BMAS 2010 - Session 3.1 - Yannick VAIARELLO

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Communication for cochlear implant

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BMAS 2010 - Session 3.1 - Yannick VAIARELLO Behavioral Modeling and System conference September 23-24, 2010 – 3.1 – 10:00 -10:30 AM

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Communication for cochlear implant

BMAS 2010 - Session 3.1 - Yannick VAIARELLO

Equivalent Channel

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Communication for cochlear implant

 Wire connection not allowed for biomedical

application => RF system

 Integration of the emitter within ear canal

 Small Battery: low power  Miniature antenna

 2.45 GHz: Good tradeoff between antenna efficiency

and transmission losses

BMAS 2010 - Session 3.1 - Yannick VAIARELLO

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Modeling

BMAS 2010 - Session 3.1 - Yannick VAIARELLO

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Behavioral Modeling and System conference September 23-24, 2010 – 3.1 – 10:00 -10:30 AM

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Modeling

BMAS 2010 - Session 3.1 - Yannick VAIARELLO

 Schematic:  Analog architecture fixed  LNA sensitivity  Transmission losses depend on patient anatomy

 Variation of transmitted power

 Critical points: PA and Propagation Channel

Modulator

(BB + RF)

Demod.

power amplifier audio signal low noise amplifier

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Modeling Heterogeneous Framework

BMAS 2010 - Session 3.1 - Yannick VAIARELLO

Analog and RF simulation:

 Electrical using SPICE simulator

Antennas and Channel:

 Electromagnetic simulator : Ansoft HFSS

Battery Lifetime model on Simulink

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Modeling Antenna and Channel Modeling

BMAS 2010 - Session 3.1 - Yannick VAIARELLO

 Electromagnetic Simulation of the

propagation channel

 Extraction of the equivalent circuit

Vtransmit Vreceive=PL.Vtransmit Rrad-e Rloss-e Rloss-r Rrad-r Le Ce Lr Cr

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Modeling Simulation Issues

BMAS 2010 - Session 3.1 - Yannick VAIARELLO

 Electromagnetic simulation:

 Using sophisticated head phantom:

1 week on a 2.8GHz Core2Duo 4GB RAM

 Using equivalent medium phantom:

1 day on a 2.8GHz Core2Duo 4GB RAM

 Analytical model:

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cart fat skin cart cart fat fat skin skin eq

t t t t t t + + + + = . . . ε ε ε ε

) exp( ). 4 (

eq m

D D PL δ π λ − =

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Modeling Simulation Issues

BMAS 2010 - Session 3.1 - Yannick VAIARELLO

 Typical attenuation in transmission channel: 25 dB  LNA Sensitivity: - 55 dBm (internal design)  Losses due to antennas efficencies: - 15 dB  Typical Transmitted Power: -15 dBm  Channel Variation => Transmitted Power and Battery

Lifetime Variations

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Modeling Transmitter Modeling

BMAS 2010 - Session 3.1 - Yannick VAIARELLO

 PA Tuning:

ref Vdd gnd modulator matching

  • ut

100 200 300 400 500 50 100 150 200 250

Pout(µW) Power consumption (µW)

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  • 15
  • 10

1.05 1.15 1.25 1.35 1.45

Vdd(V) Pout(dBm) 13

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Modeling Implementation

BMAS 2010 - Session 3.1 - Yannick VAIARELLO

 Battery Lifetime estimation:  Using Simulink (also implementable in any simulator)

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Results

BMAS 2010 - Session 3.1 - Yannick VAIARELLO

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Behavioral Modeling and System conference September 23-24, 2010 – 3.1 – 10:00 -10:30 AM

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Results

BMAS 2010 - Session 3.1 - Yannick VAIARELLO

 Battery Lifetime estimation according to channel

variations :

Tskin(mm) Tcart (mm) Tfat (mm) Loss (dB) Best 0.5 2 20 19.4 Typical 1 4 34 25.5 worst 2 6 50 30.4 Pt (µW) PPA (µW) Ptot (µW) Lifetime (days) Best 10 96 396 12 Typical 30 139 439 11 Worst 100 250 550 9

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Results

BMAS 2010 - Session 3.1 - Yannick VAIARELLO

 Battery Lifetime estimation according to other variations :  Typical => 3% efficiency ; adaptation @ -20 dB

Pt (µW) PPA (µW) Ptot (µW) Lifetime (days) Typical 30 139 439 11 Antenna adaptation @ - 10 dB 33 144 444 10.8 Antenna adaptation @ - 6 dB 36 148 448 10.7 Antenna Efficiency x2 15 115 415 11.5

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Channel noise modeling and simulation

BMAS 2010 - Session 3.1 - Yannick VAIARELLO

 Worst Case  ASK modulation: P1/P0 = 0 dBm /- 10 dBm  Noise Channel (WIFI interference ): 20 dBm @ 3m

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Conclusion

BMAS 2010 - Session 3.1 - Yannick VAIARELLO

Channel losses are very important on

biomedical transmission

This model permit to:  Know the transmitted power necessary  Evaluate multiple modulation to find the

better SNR

 Optimise the bitrate with digital modulation

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Thank you for your attention.

Any Questions ?

BMAS 2010 - Session 3.1 - Yannick VAIARELLO Behavioral Modeling and System conference September 23-24, 2010 – 3.1 – 10:00 -10:30 AM

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