Stephen Bennett
Devin Callahan
Ben Kaslon
Sushia Rahimizadeh
Connor Shapiro
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Sushia Rahimizadeh
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
Project Proposal and Purpose
Hardware Design and Implementation
o Level 1 and 2 Block Diagrams
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Software Design and Implementation
o Use Case, System Context Diagram
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Division of Labor for Major Tasks
Feasibility and Risks
Economic Viability, Environmental Aspects, Sustainability,
Manufacturability, Safety, & Impact
Schedule for the First Semester of Work
Budget
Sushia Rahimizadeh
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This project will consist of a scalable box or drawer in which
small hand-held devices or toys can be placed and
wirelessly charged.

The box will require only an external source of power in
order to be able to charge the devices.

The devices will perform all RF harvesting and charging
automatically without user input.

The user simply opens the lid, places the devices inside,
and shuts the lid. The devices do the rest.
Sushia Rahimizadeh

The purpose of this project is to demonstrate the feasibility
of scalable, commercially viable wireless charging.

It will be shown that any device is capable of being
integrated with this technology and can be charged
wirelessly in any station.
o These stations can be placed in any household, business, hotel
room, etc. and can be of varying size.
Sushia Rahimizadeh
o Heinrich Hertz – Directional, relatively high power free-space power
transmission
o Nikola Tesla – High power, omnidirectional power transmission
o Jet Propulsion Laboratory and Raytheon (1973) -- 30 kW
transferred over 1.6 km
o Topic of “Wireless Power” has been of interest since early 1900’s
Number of books that include the keyword “wireless power” since 1800, found by using Google Ngrams.
Sushia Rahimizadeh
Sushia Rahimizadeh
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“Power Transmission”
o DC electrical power into RF power
o RF power transmitted through space to some electrically far point
o Power is collected and converted into DC power at this point
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Multi-mode cavity
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No field nulls
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Field uniformity desired
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Harvest power at any point within
the cavity
Sushia Rahimizadeh

Hinged box
o Disables power transmission when open
o Enclosed by conductive mesh
o Can mount all Tx antennas and display
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RF Energy Transfer
o Uses antennas, not coupled inductors
o High overall efficiency
• High conversion efficiency (DC  RF, RF  DC , DC  DC)
• Aperture-to-Aperture efficiency

Power Management Circuits
o Supports Li-Ion and Ni-MH
Sushia Rahimizadeh

Externally-mounted display
o Unique device identification
o Power received
o Remaining charge time
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
Ben Kaslon
Ben Kaslon
Ben Kaslon
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Responsibility:
o Converts supply power into a 1W 2.2 GHz RF modulated
signal
Ben Kaslon

Responsibility:
o Convert supply power to a 2.2 GHz signal

Design Goals:
o This signal will be modulated tens of MHz around 2.2GHz in
order to improve power density uniformity in the box.
o During development, input power is supplied from lab bench
DC supply, but final design will be supplied from standard
wall outlet.
Voltage Controlled Oscillator:
Crystek CVCO55BE
Ben Kaslon
Application
Verizon and (at&T)
Unused By Consumer Devices
L2 (Military GPS)
L1 (Commercial GPS)
3G/4G
Personal Communications Service
Advanced Wireless Service
Advanced Wireless Service
Broadband Personal Communication
Broadband Personal Communication
3G/4G
Unused By Consumer Devices
Wifi
Bluetooth
Range (kHz)
Min Max
850
850
1227.6
1575.4
1700
1900
1915
1995
1850
1930
2100
2100
2400
2400
850
1227.6
1227.6
1575.4
1700
1900
1920
2000
1915
1995
2100
2400
2400
2480

2.2GHz was chosen
o Unallocated in commercial
space
o No consumer wireless
devices will be harmed by
this frequency coupling onto
the devices
o Reduced component size
o Large availability of
components operate at this
frequency
Ben Kaslon

Responsibility:
o Amplify 2.2GHz signal from the VCO to 1W

Design Goal:
o Must be designed to make the transmitter circuit as
efficient as possible.
Example Power Amplifier
Ben Kaslon

Responsibility:
o Transmits the amplified and modulated 2.2GHz signal
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Design Goal:
o Match Simulations
o Display low loss to circuit
o Well matched to the operating frequency
o Widest bandwidth possible.
Ben Kaslon

Patch antenna will be used.
o Relatively easy to design
o Small size
o Low cost
o Can be etched directly into PCB
o Lots of research available on design
Example Patch Antenna
Ben Kaslon
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Efficiency of the designed power amplifier too low
o If we are unable to design a sufficiently efficient amplifier, a
COTS amplifier will have to be used
o Ideally want 90% but will accept 50%

Design of the antenna does not match the
simulations.
o New simulations will have to be done with different, more
predictable substrates
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Non-uniform field distribution in the cavity
o Need to try a new modulation scheme
Ben Kaslon
Ben Kaslon
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Receiving arbitrarily polarized radiation within the
cavity
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Rectifying received microwave power to DC power
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Maintain optimal power transfer throughout
Ben Kaslon
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Responsibility:
o Receive microwave power
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Design Goals:
o Polarization diversity
o Harmonic rejection
o Low reflections at fundamental frequency
Ben Kaslon
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Rectifier input impedance is a function of:
o Frequency
o Power
o DC Load
o Harmonic terminations

Responsibilities:
o Ensuring optimal power transfer between antenna and rectifier
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Design Goals:
o Achieve a low reflection coefficient
o Low insertion loss
o A precise, common impedance
Ben Kaslon
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Responsibilities:
o Rectify microwave power to DC power
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Design Goals:
o Maximize rectification efficiency
o Low insertion loss
o High switching speed
o Smaller devices (smaller junction capacitance).
Ben Kaslon
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Sub-Operational Efficiencies
o Increasing power transmitted into cavity
o Antenna matching circuit redesign
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Interference from device
o Isolation will have to be introduced
Connor Shapiro
Connor Shapiro

Responsibilities:
o Charge controlling
• Ni-MH
• Li-Ion
o Battery monitoring
• Generation of
UI/display data
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Design Goals:
o Maximize boost converter efficiency
o Minimize microcontroller power consumption
Connor Shapiro
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Battery over-charging
o Prioritize cell protection
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No power to turn on microcontroller – total system failure
o Specialized cold-start circuit
Connor Shapiro
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Ni-MH Charge Cycle
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o Constant-Current &
o Constant-Current
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End-of-charge based on
𝑑𝑉
− following peak V
𝑑𝑡
Li-Ion Charge Cycle
Constant-Voltage
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End-of-charge based
end of current-draw
Connor Shapiro
Connor Shapiro
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Antenna receives device status information
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Microcontroller routine to translate data to generic display
instructions
Connor Shapiro
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Small compact LCD Display
Designed to interface easily with
any MCU
Can be used to display any generic
shapes
Cycle through displaying data for
each device
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
Stephen Bennett
Stephen Bennett
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Power Manager
Rectified power detection
Power management
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o Control boost converter to
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produce correct battery
charging profile
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Monitor voltage and
current going to
chargeable device
Packetize power data and
device ID for transmission
to display circuit
Display Manager
Decode power data
packets
Convert received data to
appropriate display format
Stephen Bennett
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Responsibilities:
o Transceivers
• Sending/receiving data at appropriate frequency
• Outputting clean signal to microcontroller
o Microcontroller
• Translating data to display instructions
o Display
• Outputting data to user
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Design Goals:
o Display instructions are independent of received data format
o Displayed data is readable and user friendly
Stephen Bennett
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MSP430 family
o
o
o
o
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Low cost
Low power
Integrates well with CC1110
Prior experience
CC1110 Transceiver
o 315-915 MHz
o Easy integration with
MSP430 EVM
MSP430
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CC430 family
o MSP430 with integrated
CC1110
CC1110 Transceiver
Stephen Bennett
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Code rewrites due to changes in underlying hardware
o Careful code design that is as hardware-independent as possible
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Code size exceeds space on microcontroller
o Choose a microcontroller with more onboard memory
o Worst case – add external memory
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Regressions or bugs created by new code
o Use a version control system (Git) in order to keep an immutable
code history
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
Devin Callahan
Task
Sushia
Project Management
Stephen
Secondary
Design of Tx Antenna
Secondary
Tertiary
Devin

Tertiary
Tertiary
Secondary
Design of Power Amplifier
Primary
Secondary
Secondary
Primary
Design of Power Converter
Design of Microcontroller Circuit
Display Circuit
Software Design
Device Integration with System
Tertiary
harvesting,
communications
systems, and embedded
systems
Primary
Primary
Primary
Secondary
Primary
Tertiary

Secondary
Primary
Secondary
Primary
Tertiary
Tertiary
Secondary
Tertiary
Primary
background in RF theory
(Space Grant)
o Experience with VNA’s,
SA’s and RF design
software (NIST)
Stephen Bennett
o Software background in embedded wireless
communications platform (Qualcomm)
o Power management background (Space Grant)

Connor Shapiro
o Power management background (TI & coursework)
Ben Kaslon
o Antenna design with a
Secondary Secondary
Secondary
Sushia Rahimizadeh
o Research in energy
Primary
Modulation of Signal
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Connor
Primary Secondary Secondary
Construction of Box
Design of Rectenna
Ben

Devin Callahan
o Analog circuit design,
implementation, and
control (LSI)
Devin Callahan

Academic Resources
o Zoya Popovic – Faculty Advisor
• Provide guidance in power amplifier and antenna design
o Steve Dunbar – Ph.D. Student
• TI Analog/RF applications engineer willing to assist in component
selection and applications
o Sean Korhummel – Ph.D. Student
• Provide guidance in converter design

Outside research already exists
Devin Callahan
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Most required components can be purchased directly from
electronics suppliers, including:
o Voltage-controlled oscillators
o Microcontrollers
o Power transistors
o Converter inductors, diodes & capacitors
Devin Callahan

A household or business can purchase one of the boxes
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Any device outfitted with the charging hardware will be able
to be charged in any box
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Low cost to produce a unit
o Most cost found in the container
o Relatively small cost for manufacturing of electronics
Devin Callahan

Most parts are available commercially
o Voltage controlled oscillator
o Microcontroller
o Peripheral parts

Parts that are not available commercially will designed
o Need to be designed for efficiency
• Power amplifier
• Rectifier
• Antennas
o Cheap to produce
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Low maintenance expectations
o Unexpected component malfunction exempting
Devin Callahan

Main concern of the system is to ensure minimum leak of
RF power in compliance with FCC regulations

It will be easy to see if this project is working or not. Either
the battery on the device will be charged or it will not

Component tolerances will not affect the design, apart from
negligible detractions from system efficiency
Devin Callahan

Leaked power is chief concern
o The system must abide by FCC regulations by emitting no stray
power
o Also relates to overall efficiency
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No other environmental concerns
Devin Callahan

This system exhibits zero risk to the environment or the
population so long as all RF energy is kept within the box

A standard 120VAC outlet plug will eventually be used
Devin Callahan
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Convenience

RF energy transfer proof-of-concept
Devin Callahan
Devin Callahan
Component
Cost
Power Transmit Circuitry
$300
Receive Circuitry
$50
Power Management Circuitry $220
Display Circuitry
$225
Software Debugger
$100
Box Construction
$100
Batteries
$160
Miscellaneous
$100
Total
$1255
Devin Callahan
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Additional battery chemistries
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More advanced GUI
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USB Charging
Questions?