RF Energy Harvesting Principle and Researchcc.ee.ntu.edu.tw/~ykchen/1221-JLee.pdf · Biomedical Technology ... wireless sensor network using TV broadcast RF energy harvesting,”

RF Energy Harvesting

Principle and Research

Outline

Future Work and Prospect

Energy Harvesting Techniques

• RF Energy

• Vibration Energy

• Solar Energy

Introduction and Motivation

2

Energy Harvesting Architecture

• System Evaluation

• Circuit Simulation

Performance Summary

• Antenna Design

Outline



• RF Energy


• Solar Energy


3




Performance Summary

• Antenna Design


The size and power supply has been drastically

decreased for many devices in decades.

Solve the problem that the devices is at inaccessible

places. 4

Produce enough power to recharge the battery or

directly supply the electronics.

Applications

WSN in environment, agriculture, and structures

applications requires continuously available power

source with long lifetimes.

Self-powering with energy harvesting

5

Existing weather station

Satellite

Monitoring

Station

Applications

Biomedically implanted devices such as stimulator

and drug deliverer

The unchangeable power source decreases the

patient’s risk of death.

6

Outline



• RF Energy


• Solar Energy


7




Performance Summary

• Antenna Design

Solar Vibration Radio Frequency

100mW/cm2

(Under sunlight) 100 mW/cm2 1 mW/cm2

Big area Cont. vibration

is needed Low power density

High power density Easy to apply on

Biomedical Technology

Easy to get from

ambient

6%~20% >95% 50%~70%

Energy Harvesting

8

RF Energy Harvester

9

Frequency 75Hz

Peak Efficiency ~90%

Output Voltage 3~5V

Output Power > 1mW

Vibration Energy Harvester

Application Circuit

Vibration Sensor

10

11

High Input Energy × Low Efficiency

× Large Area No Need Rectifier

Solar Energy Harvester

Solar Energy Harvester

Output

Voltage 4V

Peak

Efficiency ~20%

Output

Power > 1W

11

Thermoelectric Energy Harvester

Application Circuit

Thermoelectric Sensor

Output

Voltage 3V

Peak

Efficiency ~20%

Output

Power ~ 2mW

12

Outline



• RF Energy


• Solar Energy


13




Performance Summary

• Antenna Design

RF Energy Harvesting Process

14

• Wide-Band Antenna

• Rectifier

500 MHz ~ 2.4 GHz

Output Voltage: 0.2~0.5 V

• DC-DC Converter

• Digital Controller

Transfer the original DC voltage (0.2~0.5 V) to a

Control the input impedance of DC-DC converter

to deliver a maximum power to the output.

higher usable level (e.g., 2 V)

The Limits and Current Practice (I)

Power Sources

Frequency Distance Transmitted power Received

Power Efficiency

[3] 677 MHz 4.1 km 960 kW 60 mW 16.3 %

[4] Digital TV 6.6 km N/A 15-23 mW N/A

The limits of received power in current practices:

Power Conversion Efficiency(PCE) of the Rectifier

[5] [6] [7] [8] [9]

Technology 0.3 mm 0.35 mm 0.5 mm 0.25 mm 0.18 mm

Max. PCE 33% 24% 28% 60% 67.5%

Sensitivity -14 dBm -10 dBm -17.8 dBm -22.6 dBm N/A

diodeout

out

lossout

out

in

outPCE

PP

P

PP

P

P

P

Broad-band matching means low Q resonant

The Limits and Current Practice (II)

× in

V2ant

V 2

matching1 Q

Broad-Band Matching

Low Vin will degrade the efficiency of Rectifier

The Limits and Current Practice (III)

17

Power Manager: DC-DC converter, control circuit.

• The limits of current practices: 80%

Hard to surpass.

We optimized the architectures mentioned in

[10]~[12].

Outline



• RF Energy Harvesting

• Vibration Energy Harvesting

• Solar Energy Harvesting


18




Performance Summary

• Antenna Design

Architecture

Single-Band (900MHz) RF Energy Harvesting System

19

Principle of the Circuit

We are able to approach the max. rectifier’s

efficiency by adjusting the effective Zin of the DC-DC

converter across different PIN and maintaining the

rectifier’s output at ~0.5V.

This is achieved with the auto-Zin-adjust circuit

Re

cti

fie

r’s V

ou

t @

Ma

x. E

ff.

Re

cte

nn

a E

ffic

ien

cy

*matching network

cause the efficiency

gliding, not the rectifier

*

20

High efficiency rectifier

Auto-Zin-circuit

PIN

21

The rectifier’s efficiency fast degrades with Pin due to

• Max. efficiency is maintained with Pin > -18dBm

impedance mismatching.

Auto-Zin-Adjust circuit

Adjusts the length of Toff and therefore the effective Zin

of the DC-DC converter to maintain the rectifier’s

efficiency

• If Vd > Vout Zin is too high the counter will count

down

To decrease Toff, increase average load cur., and

decrease effective RL

• If Vd < Vout Zin is too low the counter will count up

To increase Toff, decrease average load cur., and

increase effective RL

Toff Tuning Circuit

Frequency divider with 6-bit configuration

Toff can be 3x~320x the clock period

3-bit Selector

÷2 ÷4 ÷8 ÷16 ÷32

23

Tn,Tp generator

Tn generator:3x of clock period

Tp generator :1x of clock period

24

• Effmatching = = 87%

• Effrectifier = = 83%

• EffDC_DC = = 74%

Performance Calculation

in_rectifier

in_matching

P

P

in_DC_DC

in_rectifier

P

P

out_DC_DC consumption

in_DC_DC

P P

P

-

Eff_totsl = Effmatching × Effrectifier × EffDC_DC = 54%

25

Power Summary: estimated by Friis equation

Outdoor (GSM/TV base station): 490 mW

Indoor (Cell Phone and WLAN): 202.5 mW

Received power at least 100 mW.

Startup Circuit

During startup phase, there is no load current. With

enough Pin (-15dBm at TT corner 27oC), the

rectifier’s output can reach > 0.6V.

• Using an oscillator that is able to oscillate with its

supply voltage less than 0.6V to control the DC-DC

converter, the output voltage can be boosted to 1.2V

• This zero startup circuit work with AC sources (ex.

RF or vibration) without precharge.

26

Outline







27




Performance Summary

• Antenna Design

Antenna a.

Frequency (GHz)

• Frequency

DTV 470~840

500 MHz~900 MHz

• Size

190×15 mm2

• Max. Gain

> 2dB S

11 (

dB

)

GSM 900

28

Antenna b.

Frequency (GHz)

GSM900

DCS1800, GSM1900,

WiMAX2350, WLAN2400

GPS1575

• Frequency

GSM/GPS/Wi-Fi

• Size

90×50 mm2

• Max. Gain

> 2dB S

11 (

dB

)

29

Antenna c.

Frequency (GHz)

802.11a

• Frequency

3 GHz~10 GHz

• Size

30×30 mm2

• Max. Gain

> 4dB

S11 (

dB

)

30

Antenna

Size Comparison

31

[13] a b c

[13]

Outline







32




Performance Summary

• Antenna Design

The performance is much better than others.

State-of-the-Art (RF)

This Work RF[14] RF[15] RF[16]

Process 0.18mm 130nm 90nm 250nm

Frequency 890-920MHz 915MHz/1GHz 915MHz 906MHz

Min. Input

Power -18dBm N/A -18dBm -22.6dBm

Max. Output

Power 113mW

@ － 5dBm* 140mW 9mW N/A

Matching Eff. 87.8%

@ －15dBm N/A 56.8% N/A

Rectifier Eff. 83%

@ －15dBm 65%

16% @ -15dBm

60% @ - 7dBm

DC-DC Eff. 74.4%

@ －15dBm 75% N/A N/A

Max.Total Eff. 54.2%

@ －15dBm N/A N/A

60% @ - 7dBm

Output Voltage 2V 1.2V 1.2V @ RL=1M 1.4V @ RL=1.32M

*The total Eff is 36% @－5dBm

33

Outline







34




Performance Summary

• Antenna Design

Future Work

Construct an over-1mW energy harvesting system by

combining multi-harvester.

• Intelligent frequency-hopping RF energy harvesting

system

Analyze trade-off between efficiency and wideband

matching, targeting max. power transfer

Use power sensor to search for band with max.

energy and dynamically tune the matching network

• Multi-sources energy harvesting power manager

Adjust ff1 of DC-DC converter to change the

loading for each ZHout of different harvesters

35

Milestones

36

1st Year

• Fully study all possible solutions, and finish the

energy harvesting circuit designs for the RF power.

2nd Year

• Use power sensor to search for band with max.

energy and dynamically tune the matching network

3rd Year

• An mW-level (>1mW) energy harvester prototype will

be presented.

• By sensing the frequency band with the most sufficient power, we will switch the corresponding rectenna to

a single DC-DC converter.

• Survey other energy solutions for researching

multi-sources energy harvesting power manager

Reference (I)

[1] Federal Communications Commission (FCC) Codes of Regulation, U.S., Part 15,

Low Power Broadcasting, available at < www.fcc.gov>.

[2] U. Bergqvist et al., “Mobile telecommunication base stations-exposure to

electromagnetic fields, Report of a short term mission within COST-244bis,”

COST-244bis short term mission on base station exposure, 2000.

[3] Alanson Sample and Joshua R. Smith, “Experimental results with two wireless

power transfer systems,” Proceedings of the 4th international conference on

Radio and wireless symposium, pp. 16-18, Jan. 2009.

[4] H. Nishimoto, Y, Kawahara, and T. Asami ,“Prototype implementation of

wireless sensor network using TV broadcast RF energy harvesting,”

Proceedings of the 12th ACM international conference adjunct papers on

Ubiquitous computing, pp. 355-356, Sept. 2010.

[5] T. Umeda, H. Yoshida, S. Sekine, Y. Fujita, T. Suzuki, and S. Otaka, “A 950-MHz

rectifier circuit for sensor network tags with 10-m distance,” IEEE J. Solid-State

Circuits, vol. 41, no. 1, pp. 35-41, Jan. 2006.

[6] H. Nakamoto, D. Yamazaki, T. Yamamoto, H. Kurata, S. Yamada, K. Mukaida, T.

Ninomiya, T. Ohkawa, S. Masui, and K. Gotoh, “A passive UHF RF identification

CMOS tag IC using ferroelectric RAM in 0.35- um technology,” IEEE J. Solid-

State Circuits, vol. 42, no. 1, pp. 101-110, Jan. 2007.

[7] U. Karthaus and M. Fischer,“Fully integrated passive UHF RFID transponder IC

with 16.7- W minimum RF input power,”IEEE J. Solid-State Circuits, vol. 38,

no. 10, pp. 1602-1608, Oct. 2003.

37

Reference (II)

[8] T. Le, K. Mayaram, and T. Fiez, “Efficient Far-Field Radio Frequency Energy

Harvesting for Passively Powered Sensor Networks,” IEEE J. Solid-State

Circuits, vol. 43, no. 5, pp. 1287-1302, May 2008.

[9] Koji Kotani, Atsushi Sasaki, and Takashi Ito, “High-Efficiency Differential-Drive

CMOS Rectifier for UHF RFIDs,” IEEE J. Solid-State Circuits, vol.44, no.11, pp.

3011-3018, Nov. 2009.

[10] E. Carlson, K. Strunz, B. Otis, “20mV Input Boost Converter for Thermoelectric

Energy Harvesting,” Digest of Symposium on VLSI Circuits, pp.162-163, June

2009.

[11] I. Doms, P. Merken, C. Van Hoof, and M. C. Schneider, “Comparison of DC-DC

converter architectures of power management circuits for thermoelectric

generators,” EPE, pp. 1-5, Sept. 2007.

[12] I. Doms, P. Merken, R. P. Mertens, and C. Van Hoof, “Capacitive power-

management circuit for micropower thermoelectric generators with a 2.1mW

controller,” ISSCC Dig. Tech. Papers, pp. 300-615, Feb. 2008.

[13] P. Li, X. Jiang, X. Liu, H. Shi, and X. Lu,” Research on the relation between

Printed Log-Periodic Antenna's feed and bandwidth,” IEEE Signals Systems

and Electronics, vol. 2, pp. 1-3, 2010.

[14] S. O’Driscoll, S. A. Poon, and T. H. Meng, “A mm-sized implantable power

receiver with adaptive link compensation,” IEEE ISSCC Dig. Tech. Papers,

pp.294–295, Feb. 2009

38

Reference (III)

[15] G. Papotto, F. Carrara, and G. Palmisano, “A 90-nm CMOS Threshold-

Compensated RF Energy Harvester,” IEEE J. Solid-State Circuits, vol. 46, no. 9,

pp. 1958-1997, Sept. 2011.

[16] T. Le, K. Mayaram, and T. Fiez, “Efficient far-field radio frequency energy

harvesting for passively powered sensor networks,” IEEE J. Solid-State Circuits,

vol. 43, no. 5, pp. 1287–1302, May 2008

39

Documents

RF Energy Harvesting Principle and Researchcc.ee.ntu.edu.tw/~ykchen/1221-JLee.pdf · Biomedical Technology ... wireless sensor network using TV broadcast RF energy harvesting,”