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Power Management and Communication for Remotely Power Management and Communication for Remotely

Powered Sensor NodesPowered Sensor NodesMehrdad Azizi, and Catherine Dehollain

Radio Frequency Integrated Circuit Group (RFIC), Ecole Polytechnique Fédérale de Lausanne (EPFL)

IntroductionThis research focuses on development of wirelessly powered integrated circuits (ICs).This research focuses on development of wirelessly powered integrated circuits (ICs).

The circuits should be able to wirelessly communicate with the base station and read

the data from various sensors or control different actuators.

The Main Challenges:

Implementing the internal circuits of the sensor node with low power consumption.

Increasing the efficiency of wireless power transmission.

Example ApplicationsECG Monitoring SystemBlood Pressure Monitoring System

J. Yoo, et al., “A 5.2 mW Self-Configured Wearable Body Sensor

Network Controller and a 12 μW Wirelessly Powered Sensor for a

Continuous Health Monitoring System,” IEEE Journal of Solid-State

Circuits, Jan 2010.P. Cong et al., “A Wireless and Battery less 10-Bit Implantable Blood Pressure Sensing Microsystem

With Adaptive RF Powering for Real-Time Laboratory Mice Monitoring,” IEEE Journal of Solid State Intraocular Pressure & With Adaptive RF Powering for Real Time Laboratory Mice Monitoring,” IEEE Journal of Solid State

Circuits, Dec. 2009.

Cardiac PacemakerCochlear Implants

Intraocular Pressure &

Temperature Monitor

S.Lee, et al., "A Programmable Implantable Micro-Stimulator

SoC with Wireless Telemetry: Application in Closed-Loop

Endocardial Stimulation for Cardiac Pacemaker,“ in ISSCC cochlearamericas.com

Y. C. Shih, T. Shen, and B. P. Otis, “A 2.3 uW

wireless Intraocular pressure/temperature

monitor,” IEEE Journal of Solid State Circuits, vol.

System Building Blocks

Endocardial Stimulation for Cardiac Pacemaker

Digest of Technical Papers, Feb. 2011, pp 44-45.

” IEEE Journal of Solid State Circuits

46, no. 11, pp. 2592-2601, Nov. 2011.

System Building Blocks

Implantable

SensorsADC

Sensor

Interface

Processing

Unit

Power & Clock

Power

ManagementCommunication

Data @ VDC@ 13.56 MHz

Data @

868 MHz Remotely Powered Integrated Circuit

Receiver

Base Station

PowerPA

Base Station

VS

VDC

Remote Powering Remote Powering Main Blocks for Wireless Power Transfer:

Functions of Different Blocks:PA is converting the DC power from

Level AdaptivWireless Voltage Regulation PA is converting the DC power from

the battery to AC power for

coupling.

L1 & L2 are coupling energy from

base station to remotely powered

VDD

Level

Detector

Adaptiv

Supply

base station to remotely powered

side.

Rectifier is converting coupled AC

voltage to DC voltage.

L1 L2

PAC1

C2

Rectifier

CL

RegulatorM12

VS Class E

Processing

Blocks

T PA Coupling Re ctifier Re gulatorη = η ×η ×η ×ηTotal Link Efficiency:

voltage to DC voltage

Regulator is stabilizing the voltage for

processing blocks.

Wireless Voltage Regulation can be

used to compensate the variation of

Base Station Remotely Powered Node

Skin

T PA Coupling Re ctifier Re gulatorη = η ×η ×η ×ηTotal Link Efficiencyused to compensate the variation of

the coupling between the inductors.

Performance of the Fabricated Rectifier:

Bias Vb1

m

VRec

Rectifier Performance

Technology 0.18 um

Frequency 13 56 MHz

CL

Mp1MN1C4C1

MN2 Mp2C3 C2

Bias Vb2

250 um

105 u

m

10 ns

500 mV

VIN+

VIN-

VIN=2.1 VP

RL=9.1 KOhm

GND ref

Frequency 13.56 MHz

Output Power 300 uW

Output Voltage 1.65 V

Peak Input Voltage 2 1 VPeak Input Voltage 2.1 V

PCE (Simulated) 85 %

PlaCiTUSPlaCiTUSPlaCiTUSPlaCiTUS RTD 2010PlaCiTUSPlaCiTUSPlaCiTUSPlaCiTUS

Power Management and Communication for Remotely Power Management and Communication for Remotely

Powered Sensor NodesPowered Sensor NodesMehrdad Azizi, and Catherine Dehollain

Ecole Polytechnique Fédérale de Lausanne (EPFL)

Low Power Communication Standard Transmitter Low Power TransmitterStandard Transmitter: Low Power Transmitter:

Free Running

Oscillator

Digital

ModulatorDAC

Mixer

PAData from

Data from

SensorsFrequency

Synthesizer

Data from

Sensors

Standards transmitters are sutiable for high data

rates and require power hungry blocks like

frequency synthesizers and power amplifiers

Low data rate of biomedical signals and short

communication range make it possible to use low

precision transmitter by directly modulating the

free running oscillatorfrequency synthesizers and power amplifiers.

Performance of the Fabricated Transmitter:

free running oscillator.

RAdjust

M4

M1

C1

M2

M3

120 u

m

Digital

Control

VSupply

M3 M4

Oscillator PerformanceC2

190 umL1

Off Chip

C2C1Technology 0.18 um

External Inductor 27 nH

Frequency 700 – 802 MHz (5 Bit) M1 M2

RAdjust1.5 cm

External Inductor as

Transmitter Antenna Supply Voltage 1 V

Supply Current 65 – 176 uA (4 Bit)

Data

Demonstration of the Concept

V

L1 L2

PAC1

C2 CLReg.

M12

VS Class ETransmitter

VDC

L3 ReceiverSensor

Interface

Base Station Sensor Node Base Station

Interface

Remote Powering Data Communication

Performance of Different Blocks:

Data Transmitter

Operation Frequency 868MHz

Power Consumption 840 uW

Data Rate 12 Kbps

Data Receiver

Class E PA

Operation Frequency 13.56 MHz

Power Consumption 370 mW

Data Receiver

Operation Frequency 868 MHz

Data Rate 12 Kbps

Sensitivity -85 dBm

Power Consumption 152 mW

Data Link Operation Distance 40 cm

System Setup:

Rectifier & Clock generationRectifier & Clock generation

Rectified Voltage 4 V

Regulated Voltage 3 & 1.8 V

Clock Frequency 192 KHz

Transmitter

Sensor

Remotely

Powered

Power

Amplifier

Receiver

Received Data

Power Link Operation Distance 1.5 cm

4.3 %Link Efficiency: PA+ Coupling+Rectifier

Clock Frequency 192 KHz

Powered

Module

4.3 %Link Efficiency: PA+ Coupling+Rectifier

Expected Contributions

This research aims to improve the already existing platforms with:This research aims to improve the already existing platforms with:

Intelligent usage of the harvested power by modifying the system level design.

Extending the system operation to multiple implantsExtending the system operation to multiple implants.