Smart Dust: Unique Low Power Flexible Sensor Networks

Maryland Sensor Network GroupNeil Goldsman, Martin Peckerar, Quirino Balzano,

Shuvra Bhattacharyya, Reza Ghodssi, Gilmer Blankenship

Dept. of Electrical and Computer EngineeringUniversity of Maryland College Park

Outline: Focus on Hardware for Achieving Smart Dust Motes and Working Network

1. Overview

2. Power Efficient Micro RF Circuits

3. Digital Low Power Circuits and Networking

4. Ultra Small Antennas

5. Energy: Micro Super Capacitor-Battery

6. Energy Harvesting: RF & RF

Overview: Smart Dust Hardware

Smart Dust Node• Analog Transceiver• Microprocessor

– Communication and Sensor Control

– Decision making

• Micro-Battery• Energy Harvesting• Micro-Antenna Smart Dust Particle

~1mm

/power

Low Power Transceiver Design

Thomas Salter, Bo Yang, Bo Li, Yiming Zhai and Neil Goldsman

Work Summary• Last January 2008 Review:

– Tested 2.2GHz OOK receiver. • Successfully demodulated digital signal• Still required DC bias, integration with transmitter, integration with digital control,

and integration with antenna.– Tested 2.2GHz OOK Transmitter:

• Operated but frequency lower than expected.• Individual die components operated in accordance with design

– Initial studies for benefits of FSK Transceiver began • Current February 2009 Review:

– 2.2GHz OOK Receiver and Transmitter fabricated and operating as designed, communicating proved in test.

– Integrated Transmitter and Receiver onto one chip, PCB test hardware developed

– Improved isolation of transmitter and receiver– Designed bias circuits, under fabrication for 2.2GHz OOK receiver– Designed and fabricated and Tested: 2.2GHz FSK.– Designed and fabricated 10GHz LNA– Designed 20GHz FSK, under fabrication.– Designed 20GHz ASK, under fabrication.– Fabricated part COTS part custom Transceiver with 2cm footprint – Initial studies for UWB transceiver began.

Data rate: 20.16kHz (up to 300kHz)

Yellow: RX output, -0.6 ~0.6V, AC coupling (x5 cable)

Blue: TX fed-in data: 0~0.9V generated by function generator

Communication between 2.2GHz TX-RXTX

RX

Layout Simplified Schematic Drawing

Measured results

2.2 GHz Transceiver with on chip Power Control switch

RF Switch

RX

TX Power rail Control Switch

2.2GHz FSK Receiver using Ultra Low Power Mixer

• Signal at buffered osc

• BFSK Input: 2.2GHz+8MHz freq modulation

• 8MHz lock-in frequency (limited by signal generator)

• Output of FM receiver.

• FM Input: 2.2 GHz FM+1MHz modulation

Mixer

Receiver Test Results:

20GHz Receivers20 GHz ASK Receiver, under fabrication 20 GHz FM Receiver, under fabrication

Can detect a 2MHz freq difference in 35MHz (20.719~20.754GHz) lock-in range

Ultra Low Power mixer and amplifier

OOK Receiver: Fabrication and Results

• fabricated utilizing 130 nm IBM process

1.00E-06

1.00E-05

1.00E-04

1.00E-03

1.00E-02

1.00E-01

1.00E+00

0.38 0.39 0.4 0.41 0.42 0.43 0.44 0.45

BE

R

LNA Bias Voltage

BER vs RF Bias

-83 dBm RF Signal Strength

-90 dBm RF Signal Strength

Improvement Over the Past Year

New Generation Measurements

Receiver PerformanceSensitivity (BER=10-3) -90 dBmPower Consumption 1.55 mWEnergy per Bit 1.5 nJ/bitData Rate 1 Mbps

Multi-Stage LNA PerformanceGain 45 dBPower Consumption 1.5 mWNoise Figure 3.6 dB

RF Scavenging DemodulatorGain vs Voltage Rectifier 17.6 dBPower Consumption 0 mW

BasebandVoltage Gain 30 dBFilter Bandwidth (3dB) 1 MHzPower Consumption .05 mW

Prior Generation Measurements

Receiver PerformanceSensitivity (BER=10-3) -50 dBmPower Consumption 2.77 mW

Energy per Bit 2.77 nJ/bitData Rate 1 Mbps

Single-Stage LNA PerformanceGain 13 dBPower Consumption 2.7 mWNoise Figure 3.4 dB

RF Scavenging DemodulatorGain vs Voltage Rectifier 10.6 dBPower Consumption 0 mW

BasebandVoltage Gain 30 dBFilter Bandwidth (3dB) 1 MHzPower Consumption .07 mW

40 dB more sensitive while consuming almost 50% less power!

Comparison to Other Receiver Designs Presented in the Literature

1.E-10

1.E-09

1.E-08

1.E-07

1.E-06

-100-80-60-40-200

En

erg

y p

er

Bit

(J

/bit

)

Sensitivity (dBm)

Comparison of Low Power Receiver Designs

Daly [30]

Porret [15]

This work

Molnar [112]

BetterLess power

More sensitive

Prior work by other in the field achieves excellent sensitivity OR very low power consumption. This work is unique in that it achieves BOTH.

Digital/Low Power Design and Optimization for the

Maryland Smart Dust Project

Chung-Ching Shen, Roni Kupershtok, Shuvra Bhattacharyya and Neil Goldsman, with

contributions from William Plishker

February, 2009

Application development

Implementation using C

Implementation using Verilog

Design toolIAR Embedded Workbench

Compile source code to generate hex format

output file

Download hex file to hardware prototypes

Design Flows for the Smart Dust Digital System

software

hardwareDesign toolVerilog Simulator (ModelSim)

Design toolFPGA Synthesis (Xilinx ISE)

Download binary file to Xilinx FPGA

Design toolSynopsys Synthesis

FloorplanningPlacement

Routing

Fabrication

MC

U p

latf

orm

FP

GA

pla

tfo

rm

AS

IC

15

ReceivePacket

Core

TransmitPacket

PacketFilter

ClockCounter

Control

Unit

PreSync

ControlSense

Design Summary for the Smart Dust Digital ASIC

Application– Distributed Line-crossing

Recognition (DLCR)

Design summary– 8 major modules and12 sub

modules for implementing DLCR algorithm and TDMA protocols

– All the modules have been implemented with Verilog-HDL.

– All the modules have been tested and verified with a FPGA developing platform.

– I/O interfaces are designed for interacting with analog transceiver modules

Mixed-signal Integration for the Smart Dust Digital/Analog ASICs

DigitalASIC

Analog transceiver modules Smart dust digital ASIC

TX control

RX control

TX data

RX data

17

Fabricated Chip for the Smart Dust Digital ASIC

Process: MOSIS AMI 0.5 µm Voltage: 5 VTarget Freq: 20KHzPower : 1.2 mWChip Size: 2.4 mm2 Pads: 40 (including test pins)

Process: IBM 0.13 µm Voltage: 1.2 VTarget Freq: 20KHzPower : 0.014 mWChip Size: 1.0 mm2 Pads: 20 (including test pins)

Process: MOSIS AMI 0.5 µm Chip Size: 2.4 mm2

# of Transistors: ~ 30,000

18

Testing Results for the Smart Dust Digital ASIC

ASIC 0

ASIC 1ASIC 0: Transmitted data

ASIC 1: Have received data and validated it

Data validation: ID must be matched as well as parallel bit check

ASIC 0 transmits data to ASIC 1via wired connection

19

Generations for the Smart Dust Mote

2cm

1.2

cm

1.4cm

PCB design

RX

TX

Chip design0.24cm

0.2

4c

m

0.2cm

0.2

cm

Fabrication

Packaging

Smart dust digital ASIC(microprocessor)

Smart dust transceiver

4cm

3cm

MCU MCU MCU

ASICs

FPGA-MCU

Btnode [5]

*Power: 105mWSize: 58X33mm

*CPU on, Radio RX/TX on

Power and Size Comparison for Sensor Network Hardware Systems

MicaZ [4]

*Power: 88.2mWSize: 58X32X7mm

Mica2 [6]

*Power: 117mWSize: 58X32X7mm

Mica2Dot [7]

*Power: 117mWSize: 25X6mm

SHIMMER [1]

*Power: 54mWSize: 50X25X12.5mm

SNoW5 [3]

*Power: 73.1mWSize: 50X85mm

Tmote Sky [2]

*Power: 58.5mWSize: 32X80mm

Power

Siz

e

Smart Dust

*Power: 4.8mWSize: 20X14X12mm

21

References

[1] B. Kuris and T. Dishongh. SHIMMER Hardware Guide Rev 10, October 2006. (http://www.eecs.harvard.edu/~konrad/projects/shimmer/)

[2] Moteiv Tmote Sky Datasheet, November 2006. (http://www.moteiv.com/)

[3] M. Baunach, R. Kolla, and C. Muhlberger. Snow5: a modular platform for sophisticated real-time wireless sensor networking, Institut fur Informatik, University of Wuerzburg, Technical Report 399, January 2007.

[4] MICAz Datasheet Rev A. Crossbow. (http://www.xbow.com/)

[5] BTnode rev3 Hardware Reference. ETH Zurich. (http://www.btnode.ethz.ch/)

[6] MICA2 Datasheet Rev A. Crossbow. (http://www.xbow.com/)

[7] MICA2Dot Datasheet Rev A. Crossbow. (http://www.xbow.com/)

22

Publications• Journal

– C. Shen, R. Kupershtok, S. Adl, S. S. Bhattacharyya, N. Goldsman, and M. Peckerar. Sensor support systems for asymmetric threat countermeasures. IEEE Sensors Journal, 8(6):682-692, June 2008.

– C. Shen, W. Plishker, D. Ko, S. S. Bhattacharyya, and N. Goldsman. Energy-driven distribution of signal processing applications across wireless sensor networks. Submitted to ACM Transactions on Sensor Networks.

• Conference– C. Shen, W. Plishker, and S. S. Bhattacharyya. Design and optimization of a distributed, embedded

speech recognition system. Proceedings of the International Workshop on Parallel and Distributed Real-Time Systems, Miami, Florida, April 2008.

– M. Peckerar, C. Shen, S. S. Bhattacharyya, and N. Goldsman. Integrated Multi-layer Design of Ad-Hoc Smart Small Sensor Networks. Proceedings of the Government Microcircuit Applications and Critical Technology Conference, Las Vegas, Nevada, March 2008.

– C. Shen, W. Plishker, S. S. Bhattacharyya, and N. Goldsman. An energy-driven design methodology for distributing DSP applications across wireless sensor networks. Proceedings of the IEEE Real-Time Systems Symposium, Tucson, Arizona, December 2007.

– C. Shen, R. Kupershtok, S. S. Bhattacharyya, and N. Goldsman. Design and implementation of a device network application for distributed line-crossing recognition. Proceedings of the International Semiconductor Device Research Symposium, College Park, Maryland, December 2007.

– C. Shen, R. Kupershtok, S. S. Bhattacharyya, and N. Goldsman. Design techniques for streamlined integration and fault tolerance in a distributed sensor system for line-crossing recognition. Proceedings of the International Workshop on Distributed Sensor Systems, Honolulu, Hawaii, August 2007.

– C. Shen, R. Kupershtok, B. Yang, F. M. Vanin, X. Shao, D. Sheth, N. Goldsman, Q. Balzano, and S. S. Bhattacharyya. Compact, low power wireless sensor network system for line crossing recognition. Proceedings of the International Symposium on Circuits and Systems, New Orleans, Louisiana, May 2007.

– C. Shen, C. Badr, K. Kordari, S. S. Bhattacharyya, G. L. Blankenship, and N. Goldsman. A rapid prototyping methodology for application-specific sensor networks. Proceedings of the IEEE International Workshop on Computer Architecture for Machine Perception and Sensing, Montreal, Canada, September 2006.

Efficient Antennas for Motes Dimensions << λ/4

BO YANG, XI SHAO, Q. BALZANO AND NEIL GOLDSMAN

Work summary

• Last January 2008 Review:– Fabricated FICA for 2.2 GHz /2.4 GHz with 1.1 mm x 1.1 mm ground

plane.– Tested 2.2 GHz FICA outdoor.– Measured FICA performance with in-house designed On-Off Keying

(OOK) receiver– Developed circuit model of FICA– Expected 3D integration of transceiver, with lowest form factor in the

world– Investigation of ground plane size effect under way

• Current February 2009 Review:– Applied FICA circuit model into system design optimization.– Measured 916MHz and 2.2GHz FICA radiation pattern in Anechoic

Chamber– Implemented 3D integrated transceiver, with world’s record low form

factor.– Tested 20mm x 15 mm x 15 mm radio (including FICA, radio, sensor,

battery, etc.)

Short Review of ESAs• ESA Plusses

– Small volume – More room for electronics – Attractive product looks – High tech impression– Wide applicability– Low manufacturing cost

• ESA Minuses– Adverse reactance (l or

1/c)– Low radiation resistance

(m)– Low effiency (ohmic losses)– Narrow band– Low gain– Difficult to match to 50

• ESA is: – a radiating resonator – compact and efficient – minimum ohmic losses– short transmission line

• To Radiate ESA: – Need large currents and

large e-fields over the small volume (resonance)

– Need impedance transformer to feed with 50

– Need low loss materials

An Efficient ESA: FICA (F-Inverted Compact Antenna)

• Transmision line propagation constant k=ω√LC

• Helical transmission line (high L)

• Strong coupling to ground (high C)

• Short helix resonant size

• Minimum number of turns

• Embedded reactive impedance transformer

• Strong electric dipole radiation current

2.45GHz FICA Integrated with a Mote

• The wave length at 2.45GHz is 12.24cm. • The dimension of 2.45GHz FICA is shown in the photo.

12m

m

20mm

4mm

7mm

3.5mmFull transceiver radio and battery is enclosed in the black box.

Exposed part is the antenna

Microphone sensor

FICA Radiation Pattern

FICA tested in anechoic chamber, radiation pattern matches simulation.

FICA vs. COMPETION

FICA Equivalent Circuit for System Optimization

FICA Publications• Patent:

– B. Yang, F. Vanin, X. Shao, Q. Balzano, N. Goldsman, G. Metze, Low Profile F-Inverted Compact Antenna (FICA), filed by University of Maryland, Jun. 2007, patent pending.

• Journal:– B. Yang, X. Shao, Q. Balzano, N. Goldsman, G. Metze, “916 MHz F-Inverted

Compact Antenna (FICA) for highly integrated transceivers,” Antennas and Wireless Propagation Letters, to be published.

• Conference:– B. Yang, X. Shao, Q. Balzano, N. Goldsman, “ Integration of small antennas

for ultra small nodes in wireless sensor networks,” in IEEE International Semiconductor Device Research Symposium Dig. (ISDRS), College Park, MD. USA., Dec. 2007.

– B. Yang, F. Vanin, C. Shen, X. Shao, Q. Balzano, N. Goldsman, C. Davis, “A low profile 916 MHz F-Inverted Compact Antenna (FICA) for wireless sensor networks,” in IEEE Antenna and Propagation International. Symposium. Dig., pp. 5419-5422, Honolulu, HI. USA., Jun. 9-15, 2007.

– C-C. Shen, R. Kupershtok, B. Yang, F. Vanin, X. Shao, D. Sheth, N. Goldsman, Q. Balzano, S. S. Bhattacharyya, “Compact, low power wireless sensor network system for line crossing recognition,” in IEEE International Symposium on Circuits and Systems (ISCAS), pp. 2506-2509, New Oreland, LA. USA., May 27 -30, 2007.

CONCLUSION

• Extremely small antenna

• High efficiency for size

• Bandwidth compatible with theoretical q

• Radiation: isotropic as possible

• Performance better than or comparable to larger commercial antennas

433 MHzBody Antenna

Q. Balzano, Bo Yang, Xi Shao, Neil Goldsman

Presented in Classified Review

Flexible Thin Film Battery/Supercapacitor Hybrid

Power SourcesMartin Peckerar, Yves Ngu, Zeynep Dilli, Mahsa Dornajafi, Kwangsik Choi, Myunghwan Park and

Neil GoldsmanDepartment of Electrical and Computer

EngineeringUniversity of Maryland

College Park, MD 20742

Project Goals

• To achieve a mechanically flexible power source that can conform to a range of surface topologies (electronic packaging material, bridge abutments, supporting struts, etc.)

• To create a galvanic cell/supercapacitor hybrid capable of long term, low power level sourcing as well as power “burst mode” operation

• To create a power supply that is more easily charged by RF (and mechanical energy scavenger) sources: e.g. , a cell that recharges at low (~1V) voltage

• To create an “environmentally safe” power source to eliminate the toxicity issues associated with lithium

Double stacked cell

Negative lead

Positive lead

Zinc sheetFilter paper + electrolyte

Powder mixGold coated graphite

Lexan package

Negative lead

Positive lead

Zinc sheetFilter paper + electrolyte

Powder mixGold coated graphite

Lexan package

Negative lead

Positive lead

Negative lead

Positive lead

Single cell

The electrolyte is made of a solution of ethylene glycol, ammonium hydroxide, boric acid + nitric acid OR phosphorus acid

We Have Successfully Run Smart Motes with the RuOx

Batteries

We Have Demonstrated Low-Voltage RF charging

We Have Demonstrated “Burst-Mode” Operation

We Have Driven Flexible Electronics Platforms With the RuOx Cells

Comparison of Thin Film Galvanic Cells

Conclusions

• WE HAVE DEMONSTRATED:– A FLEXIBLE THIN-FILM POWER SOURCE WITH

GREATER STORAGE CAPACITY THAN ANY OTHER APPEARING IN THE LITERATURE

– WE HAVE OPERATED THE “SMART DUST” MOTE IN FULL T/R MODE FOR OVER 4.5 MINUTES

– THE CELL EXHIBITS INTERESTING “REGENERATION” BEHAVIOR

– WE HAVE DEVELOPED A LOW VOLTAGE RECHARGING CELL

– WE HAVE USE OUR CELL TO OPERATE FLEXIBLE ELECTRONICS

Future

• Ultra Low Power Transceivers– Ultra Wide Band Radios– Broad Band Antennas– Dedicated Signal Processing & Digital Control

• Batteries for Networks– Planar– Geometrically Configurable– Remote Chargeability