seminar report on wireless spintronics modulation
DESCRIPTION
seminar reportTRANSCRIPT
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 1 METS school of Engg, Mala
1. INTRODUCTION
Wireless spintronics modulation is a new communication concept that can be adapted
to STNO characteristics. By exploiting nanotechnology, spintronics devices can be easily
realized in a STNO array structure, and each STNO can directly be assigned to many RF
frequencies. First, data are carried at each frequency of each STNO. Many channels can be
assigned due to wideband operation. Second, we select OOK modulation,which is not only a
non-coherent communication method for wireless transmission but also allows wireless
transmission of data via air without changing frequency, even in the case of STNO non-
linearity phenomena.
We then propose a spin RF-direct FDM modulation concept that is adaptable to
STNO.It facilitates STNO communication at higher data rates according to the number of
STNOs within an array, because OOK is executed with each frequency assigned at each
STNO with the targeted frequency.
It has been reported that spintronics oscillators can feasibly be used for wireless
communication by using frequency shift keying (FSK) modulation. Because a spintronics
oscillator has characteristics of wideband operation, as well as fast rising and falling time
when the signal is settling, it can transmit at high data rates with multiband operation in the
air. Moreover, devices applying a spin torque nano-oscillator (STNO) can be realized with a
small form factor because the STNO can be fabricated with hundreds of nanometer size.
However, spintronics oscillators still have a low signal level and poor linewidth thus
impeding their use as a substitute for LC oscillators for wireless communication. Another
difficulty for communication applications is nonlinearity of the output signal when frequency
modulation is applied in the spintronics oscillator . The current flowing through a STNO not
only changes the amplitude ofthe oscillation signal but also shifts its frequency. This presents
challenges for wireless communication with an STNO at an assigned frequency.
Communication is targeted near field communication with low power consumption
by not amplifying the signal at the low power level of the STNO. The proposed scheme is
expected to be competitively executed in near field communication (NFC) with high speed
communication, low power consumption, and small size at relatively low cost.Wireless
communication is the transfer of information between two or more points that are not
connected by an electrical conductor.The most common wireless technologiesuse radio.
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 2 METS school of Engg, Mala
With a radio waves distances can be short, such as a few meters for the television or as far as
thousands or even millions of kilometers for deep space radio communications. It
encompasses various types of fixed, mobile, and portable applications, including two-way
radios, cellular telephones, personal digital assistants (PDAs), and wireless networking.
The prosposed communication uses on off keying modulation,which the simplest
form of amplitude-shift keying (ASK) modulation that represents digital data as the presence
or absence of a carrier wave. In its simplest form, the presence of a carrier for a specific
duration represents a binary one, while its absence for the same duration represents a binary
zero. Some more sophisticated schemes vary these durations to convey additional
information. It is analogous to unipolar encoding line code.
On-off keying is most commonly used to transmit Morse code over radio frequencies
(referred to as CW (continuous wave) operation), although in principle any digital encoding
scheme may be used. OOK has been used in the ISM bands to transfer data between
computers. OOK is more spectrally efficient than frequency-shift keying, but more sensitive
to noise when using a regenerative receiver or a poorly implemented superheterodyne
receiver.
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 3 METS school of Engg, Mala
2. WIRELESS COMMUNICATION
Wireless communication is the transfer of information between two or more points that
are not connected by an electrical conductor.The most common wireless technologies use
radio. With radio waves distances can be short, such as a few meters for television or as far
as thousands or even millions of kilometers for deep-space radio communications. It
encompasses various types of fixed, mobile, and portable applications, including two-way
radios, cellular telephones, personal digital assistants (PDAs), and wireless networking.
Other examples of applications of radio wireless technology include GPS units, garage
door openers, wireless computer mice, keyboards and headsets, headphones, radio receivers,
satellite television, broadcast television and cordless telephones.Some what less common
methods of achieving wireless communications include the use of other electromagnetic
wireless technologies, such as light, magnetic, or electric fields or the use of sound. Wireless
operations permit services, such as long-range communications, that are impossible or
impractical to implement with the use of wires.
Fig 2.1 Wireless communication concept
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 4 METS school of Engg, Mala
Fig 2.2 Devices in wireless network
The term is commonly used in the telecommunications industry to refer to
telecommunications systems (e.g. radio transmitters and receivers, remote controls etc.)
which use some form of energy (e.g. radio waves, acoustic energy, etc.) to transfer
information without the use of wires.Information is transferred in this manner over both short
and long distances
2.1 ADVANTAGES
Communication has enhanced to convey the information quickly to the
consumersWorking professionals can work and access Internet anywhere and anytime
without carrying cables or wires wherever they go. This also helps to complete the work
anywhere on time and improves the productivity.
Doctors, workers and other professionals working in remote areas can be in touch with
medical centres through wireless communication.Urgent situation can be alerted through
wireless communication. The affected regions can be provided help and support with the help
of these alerts through wireless communication.Wireless networks are cheaper to install and
maintain.
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 5 METS school of Engg, Mala
3. SPINTRONICS
The basic principle involved is the usage of spin of the electron in addition to mass
and charge of electron. Electrons like all fundamental particles have a property called spin
which can be orientated in one direction or the other called spin-up or spin-down like a top
spinning anticlockwise or clockwise. Spin is the root cause of magnetism and is a kind of
intrinsic angular momentum that a particle cannot gain or lose. The two possible spin states
naturally represent 0and 1in logical operations. Spin is the characteristics that makes the
electron a tiny magnet complete with north and south poles .The orientation of the tiny
magnet north-south poles depends on the particles axis of spin.
Fig 3.1 Electron spinning
Conventional electronic devices rely on the transport of electrical charge carriers
electrons in a semiconductor such as silicon. Now, however, physicists are trying to exploit
the spin of the electron rather than its charge to create a remarkable new generation of
spintronic devices which will be smaller, more versatile and more robust than those
currently making up silicon chips and circuit elements .
Spintronics is a technology which deals with spin dependent properties of an electron
instead of its charge dependent properties. Conventional electronics devices rely on the
transport of electric charge carries electrons. But there is other dimensions of an electron
other than its charge and mass i.e. spin. This dimension can be exploited to create remarkable
generation of spintronic devices. It is believed that in the near future spintronics could be
more revolutionary than any other technology.
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 6 METS school of Engg, Mala
To enhance the multifunctionality of an devices (for example, carrying out processing
and data storage on the same chip), investigators have been eager to exploit another property
of the electron known as spin. Spin is a purely quantum phenomenon roughly akin to the
spinning of a childs top or the directional behavior of a compass needle. The top could spin
in the clockwise or counter clockwise direction; electrons have spin of a sort in which their
compass needles can point either up or down in relation to a magnetic field.
Spin therefore lends itself elegantly to an new kind of binary logic of ones and zeros.
The movement of spin, like the flow of charge, can also carry information among
devices.One advantage of spin over charge is that spin can be easily manipulated by
externally applied magnetic fields, a property already in use in magnetic storage technology.
Fig 3.2 Concept for spin electronics
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 7 METS school of Engg, Mala
3.1. LOGIC OF SPIN
Spin relaxation (how spins are created and disappear) and spin transport (how spins
move in metals and semiconductors) are fundamentally important not only as basic physics
questions but also because of their demonstrated value as phenomena in electronic
technology.Researchers and developers of spintronic devices currently take two different
approaches.
In the first, they seek to perfect the existing GMR-based technology either by
developing new materials with larger populations of oriented spins (called spin polarization)
or by making improvements in existing devices to provide better spin filtering. The second
effort, which is more radical, focuses on finding novel ways both to generate and to utilize
spin-polarized currents that is, to actively control spin dynamics.
The intent is to thoroughly investigate spin transport in semiconductors and search for
ways in which semiconductors can function as spin polarizers and spin valves. This is crucial
because, unlike semiconductor transistors, existing metal-based devices do not amplify
signals (although they are successful switches or valves).
If spintronic devices could be made from semiconductors, however, then in principle
they would provide amplification and serve, in general, as multi-functional devices. Perhaps
even more importantly, semiconductor-based devices could much more easily be integrated
with traditional semiconductor technology. In addition to the near-term studies of various
spin transistors and spin transport properties of semiconductors, a long-term and ambitious
subfield of spintronics is the application of electron and nuclear spins to quantum
information processing and quantum computation.
The quantum mechanics may provide great advantages over classical physics in
computation. However, the real boom started after 20 Peter Shor of Bell Labs devised a
quantum algorithm that would factor very large numbers into primes, an immensely difficult
task for conventional computers and the basis for modern encryption. It turns out that spin
devices may be well suited to such tasks, since spin is an intrinsically quantum property.
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 8 METS school of Engg, Mala
Fig 3.3 Spins arrangements
The simplest method of generating a spin-polarised current in a metal is to pass the
current through a ferromagneticmaterial. The most common applications of this effect
involve giant magnetoresistance (GMR) devices. A typical GMR device consists of at least
two layers of ferromagnetic materials separated by a spacer layer. When the two
magnetization vectors of the ferromagnetic layers are aligned, the electrical resistance will be
lower (so a higher current flows at constant voltage) than if the ferromagnetic layers are anti-
aligned.
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 9 METS school of Engg, Mala
4. SPINTRONICS OSCILLATOR
Spintronics oscillators can feasibly be used for wireless communication by using
frequency shift keying (FSK) modulation . Because a spintronics oscillator has characteristics
of wideband operation, as well as fast rising and falling time when the signal is settling, it
can transmit at high data rates with multiband operation in the air.
Moreover, devices applying a spin torque nano-oscillator (STNO) can be realized
with a small form factor because the STNO can be fabricated with hundreds of nanometer
size .However, spintronics oscillators still have a low signal level(e.g., dBm measured in our
fabricated STNO) and poor linewidth (e.g., 130 MHz measured in our fabricated
STNO,meaning the phase noise is dBc at an offset of 130 MHz),thus impeding their use as a
substitute for LC oscillators for wireless communication.
Another difficulty for communication applications is nonlinearity of the output signal
when frequency modulation is applied in the spintronics oscillator . The current flowing
through a STNO not only changes the amplitude of the oscillation signal but also shifts its
frequency. This presents challenges for wireless communication with an STNO at an as-
signed frequency.
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 10 METS school of Engg, Mala
5. SPIN TORQUE NANO OSCILLATOR
Spin torque oscillators (STO) are a new class of tunable Radio frequency oscillators
in the 165GHZ range with potential use in cellphones,wireless devices,satellite
communication, and vehicle radar.
Fig 5.1 spin torque transfer
A fundamental obstacle to the rapid commercialization of this technology is the very
limited Output power of the signal. spintronics oscillators still have a low signal level and
poor linewidth thus impeding their use as a substitute for LC oscillators for wireless
communication.Difficulty for communication applications is nonlinearity of the output signal
when frequency modulation is applied in the spintronics oscillator .The current flowing
through a STNO not only changes the amplitude ofthe oscillation signal but also shifts its
frequency. This presents challenges for wireless communication with an STNO at an
assigned frequency.
Fig 5.2 Frequency vs magnetic field
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 11 METS school of Engg, Mala
It has been reported that spintronics oscillators can feasibly be used for wireless
communication by using frequency shift keying (FSK) modulation. Because a spintronics
oscillator has characteristics of wideband operation, as well as fast rising and falling time
when the signal is settling, it can transmit at high data rates with multiband operation in the
air. Moreover, devices applying a spin torque nano-oscillator (STNO) can be realized with a
small form factor because the STNO can be fabricated with hundreds of nanometer size.By
exploiting nanotechnology, spintronics devices can be easily realized in a STNO array
structure, and each STNO can directly be assigned to many RF frequencies.
5.1. SPIN TORQUE TRANSFER
Spin-transfer torque is an effect in which the orientation of a magnetic layer in a
magnetic tunnel junction or spin valve can be modified using a spin-polarized current. A
simple model of spin-transfer torque for two anti-aligned layers. Current flowing out of the
fixed layer is spin-polarized. When it reaches the free layer the majority spins relax into
lower-energy states of opposite spin, applying a torque to the free layer in the process.Charge
carriers (such as electrons) have a property known as spin which is a small quantity of
angular momentum intrinsic to the carrier.
Fig 5.3 Simple model of spin-transfer torque for two anti-aligned layers
An electrical current is generally unpolarized (consisting of 50% spin-up and 50%
spin-down electrons); a spin polarized current is one with more electrons of either spin. By
passing a current through a thick magnetic layer (usually called the fixed layer), one can
produce a spin-polarized current. If this spin-polarized current is directed into a second,
thinner magnetic layer (the free layer), angular momentum can be transferred to this layer,
changing its orientation. This can be used to excite oscillations or even flip the orientation of
the magnet. The effects are usually only seen in nanometer scale devices.
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 12 METS school of Engg, Mala
6. ON OFF KEYING (OOK) MODULATION
On-off keying (OOK) denotes the simplest form of amplitude-shift keying (ASK)
modulation that represents digital data as the presence or absence of a carrier wave. In its
simplest form, the presence of a carrier for a specific duration represents a binary one, while
its absence for the same duration represents a binary zero. Some more sophisticated schemes
vary these durations to convey additional information. It is analogous to unipolar encoding
line code.
On-off keying is most commonly used to transmit Morse code over radio frequencies
(referred to as CW (continuous wave) operation), although in principle any digital encoding
scheme may be used. OOK has been used in the ISM bands to transfer data between
computers. OOK is more spectrally efficient than frequency-shift keying, but more sensitive
to noise when using a regenerative receiver or a poorly implemented superheterodyne
receiver.
Fig 6.1 OOK modulation concept
OOK modulation is a very popular modulation used in control applications.This is
due to its simplicity and low implementation costs. OOK modulation has the advantage of
allowing the transmitter to idle during the transmission of a zero, therefore conserving
power. The disadvantage of OOK modulation arises in the presence of an undesired signal
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 13 METS school of Engg, Mala
7. FREQUENCY DIVISION MULIPLEXING
In telecommunications, frequency-division multiplexing (FDM) is a technique by
which the total bandwidth available in a communication medium is divided into a series of
non-overlapping frequency sub-bands, each of which is used to carry a separate signal. These
sub-bands can be used independently with completely different information streams, or used
dependently in the case of information sent in a parallel stream. This allows a single
transmission medium such as the radio spectrum, a cable or optical fiber to be shared by
multiple separate signals.
The most natural example of frequency-division multiplexing is radio and television
broadcasting, in which multiple radio signals at different frequencies pass through the air at
the same time. Another example is cable television, in which many television channels are
carried simultaneously on a single cable. FDM is also used by telephone systems to transmit
multiple telephone calls through high capacity trunklines, communications satellites to
transmit multiple channels of data on uplink and downlink radio beams, and broadband DSL
modems to transmit large amounts of computer data through twisted pair telephone lines,
among many other uses.
Fig 7.1 FDM channels
An analogous technique called wavelength division multiplexing is used in fiber optic
communication, in which multiple channels of data are transmitted over a single optical fiber
using different wavelengths (frequencies) of light.
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 14 METS school of Engg, Mala
8. CONCEPT:SPIN RF- DIRECT FDM WITH STNO ARRAY
Figure shows the concept of spin RF-direct modulation using a frequency division
multiplex (FDM) with a spin torque nano-oscillator (STNO) array.
Fig 8. 1 The concept of a spin RF-direct FDM modulation with a STNO array.
Here, Dn, In, and fn are nth data, current, and frequency; STNOn is the nth STNO
and MNn is a matching network for the nth frequency at the nth STNO. Wideband MN
denotes a wideband matching network and Ant is antenna. .
For the proposed modulation, two STNO are bonded at each branch of a T-junction
on a PCB, where a high pass filter (HPF) and a low pass filter (LPF) are connected on each
branch of the T-junction to transmit the modulated signal into one antenna. Each STNO
modulates by on-off keying (OOK) with digital data directly after setting on the separation of
channels for two STNOs into 700 MHz, one STNO at 3.5 GHz frequency and the other at 4.2
GHz, with consideration of the minimum sensitivity and interference related with isolation
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 15 METS school of Engg, Mala
between channels. A data rate of up to 400 Kbps is obtained at a distance of 10 mm, and the
dc power consumption is 3 mW per STNO, including logic circuit operation.
8.1.DESIGN OF SPIN M ODULATOR
In order to realize a spin RF-direct FDM modulation, we executed experiments with
two STNOs to check whether wireless communication can be realized with spintronics
oscillation, and also assessed whether the spin RF-direct FDM modulation concept was
practicable.
Fig 8.2 Frequency vs magnetic field
Figure shows the STNO oscillation characteristics of frequency depending on the
magnetic field. The signal level, at the offset point corresponding with the channel separation
between two channels from each carrier frequency, should be selected to be below the
minimum sensitivity, dBm, considering the linewidth and signal level. We thus selected
frequencies of 3.5 and 4.2 GHz with 700 MHz channel separation for two STNOs for the
channel separation to be at least three times the linewidth.A data rate of up to 400 Kbps is
obtained at a distance of 10 mm, and the dc power consumption is 3 mW per STNO,
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 16 METS school of Engg, Mala
including logic circuit operation. The PCB size is as small as 28 27 mm, including the 4.2 2.1
mm STNO array.
8.2. MATCHING THE CIRCUIT ON EACH STNO
A T-junction structure is applied to the PCB for assigning thefrequencies generated
on two STNOs to transmit a signal in the air through a single antenna.We designed matching
networks with a LPF circuit for a 3.5 GHz STNO, and a HPF circuit for a 4.2 GHz STNO to
provide operation without interference with each other, and then each output port of the
matching circuit is connected with other ports of the T-junction,taking into consideration an
antenna that will be situated at the center port of the T-junction. The STNO has the anti-
parallel magnetic resistance (MR) of 80 , where the STNO provides good signal oscillation.
A HPF circuit is applied to obtain higher isolation at 3.5 GHz as well as low insertion
loss at 4.2 GHz, and vice versa in the LPF circuit. Higher isolation and low insertion loss
cause all of the signal to flow into the antenna port of the T-junction without signal loss. We
targeted insertion loss approaching 3 dB, and signal isolation below dB in the T-junction.
Fig. 3 shows the measurement results of the T-junction. The antenna is located immediately
after the T-junction and it has a band from 3.1 to 5.2 GHz, and 2 dBi gain.
The power level transmitted through the antenna is dBm at 4.5 GHz with consider-
ation of the T-junction loss and antenna gain, and the thermal noise level is dBm in the 130
MHz STNO linewidth. The SNR in the transmitter is thus 20.4 dB. The transmission margin
is 11.4 dB, because the required SNR is 9.0 dB for the bit error rate (BER) in the OOK
system. This margin corresponds to supporting transmission up to 27 mm distance in the air
in the condition of using a receiver having no noise or gain
8.3. MODULATION AND BIASING ON STNO
An oscillation signal is generated by the current flowing through the STNO. Current
can be supplied via a current mirror circuit as a bias for a stable current supply.The current
mirror circuit is designed with two PMOS. The ratio of the transistor width for the current
mirror circuit must be set at 1:8 to reduce the leakage current to 1/8th of the current flowing
through the STNO.
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 17 METS school of Engg, Mala
Fig 8.3 Measurement results of the T-junction matching circuit.
The supplied current drives the STNO to generate oscillation. We then modulate the
STNOwith the OOK method,where the current supplied from the current mirror circuit is
switched on/off. This function is executed through a NMOS switch that enables operation of
the current mirror circuit.
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 18 METS school of Engg, Mala
9. MEASUREMENT RESULTS
Fig. 4 shows the PCB board with soldered components together with STNOs
structured in a 2 4 array for transmitting multi channel signals to one antenna.We selected
two out of the 8 STNOs and set the target frequency by controlling the magnitude of the
magnetic field, the angle of the applied magnetic field to the STNO, and the current quantity
based on STNO operation.
Fig 9.1 Fabricated PCB board with soldered components with a STNO array
We situated a RF switch between the T-junction and the antenna to monitor the
STNO output signal. The RF switch is controlled by a dip switch.To carry out the
measurements, the fabricated PCB is placed on a C-type magnetic closed circuit to apply a
magnetic field around the DUT. Constant current is applied to the electro magnet bya
precision current source,and afringingfield is generated depending on the current quantity.
The fabricated STNO could change the frequency by only around 220 MHz according to the
current flow to the STNO from 1.0 to 2.5 mA in our fabricated STNO. Thus the fringing field
is adjusted by the current quantity, and the direction of the magnetic field is also changed by
manually making the C-type magnetic closed circuit rotate for each STNO to be set to an
assigned frequency of 3.5 and 4.2 GHz, respectively.Under these measurement conditions,
we tested the transmission operation on dual frequencies modulating OOK into one antenna.
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 19 METS school of Engg, Mala
Then design a dual channel OOK receiver for verification of the transmitted signal.
The air loss is 5 dB in a distance of 10 mm, and the commercial demodulator sensitivity we
tested is dBm. We obtained a communication margin of 14 and 16 dB, because the received
signal level is -62 dBm and -60 dBm at the receiver with a system NF of 4.3 and 4.5 dB and
system gain of 15 and 17 dB at 3.5 and 4.5 GHz, respectively.This demonstrates that the
wireless technology of spintronics modulation is feasible for use in wireless communication.
Although reported that current clearly modulates pulse repetition frequency (PRF) up
to 5 MHz, in the experiments reported, in this letter the usable frequency of PRF is limited by
the bias delay driving current at the transmitter, and by a falling time of 180 nsec and a rising
time of 100 nsec for detection at the receiver. This work is verified by using the LandauLif-
shitz Gilbert Slonczewski (LLGS) equation for the STNO with a MATLAB tool,
considering parallel MR of 50 and anti-parallel MR of 80 , when 500 pF is added in the bias-
T for cancelling modulation noise.
A data rate of up to 200 kbps is obtained at each frequency in the experiment results
at a distance of 10 mm, and the power consumption is under 3 mW per STNO at these
measurement conditions. It corresponds to an energy efficiency of 15 nJ/bit.This result shows
that a data rate up of up to 400 Kbps is acquired at the STNO array.
The 15 nJ/bit obtained from the acquired consumption result is not a remarkable
achievement due to the use of commercial circuits supplied with 2 VDC; however, recent
numerical simulations suggest that current densities may be reduced to five orders of
magnitude lower than the tested STNO .If nano-scaled CMOS and new spintronics
technologies are applied, the size and power consumption of the wireless technology in this
work could approach those of the core block, i.e.,STNO. It is observed that 0.18 mW power
consumption occurs at one STNO.The core in this work has three times larger tuning range
,5.5 times smaller power consumption and much smaller size
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 20 METS school of Engg, Mala
10. ADVANTAGES
Some of the advantagesof wireless spintronics modulation are
Provide near field communication with low power consumption by not amplifying the
signal at the low power level of the STNO
Increases data rates remarkably by using a STNO array, which features the wide band
range even exceeding 100%
Low dc consumption at the micro-watt level
Nano-sized realization
Small size at relatively low cost.
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 21 METS school of Engg, Mala
11. APPLICATIONS
Can be used in near field communication (NFC)
Can implemented in mobile telephony
Adopt as a alternative for wireless communication methods
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 22 METS school of Engg, Mala
12.CONCLUSION
We demonstrated a new communication technique with spintronics technology. This
is the first report of the wireless spintronics modulation with a STNO array. The obtained
results demonstrate the possibility of increasing data rates remarkably by using a STNO
array, which features a wide band range even exceeding 100%, low dc consumption at the
micro-watt level, and nano-sized realization. However, many barriers must still be
surmounted. In view of modulation, each STNO has to be designed with operation of a
differenct frequency on the same magnetic field in order to easily realize a spin RF-direct
FDM modulation at the STNO array.This has been accomplished by the STNO employing
wideband frequency variation according to the dc bias current, or a different value or
direction of the anisotrophic field.Nevertheless, the proposed scheme is expected to be
competitively executed in near field communication (NFC) with high speed communication,
low power consumption, and small size at relatively low cost.
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 23 METS school of Engg, Mala
REFERENCES
[1] M. Manfrini, T. Devolder, J. Kim, P. Crozat, C. Chappert, W. Roy, and L.
Lagae,Frequency shift keying in vortex-based spin torque oscillators, J. Appl. Phys., vol.
109, p. 083940, 2011.
[2] I. N. Krivorotov, N. C. Emley, J. C. Sankey, S. I. Kiselev, D. C. Ralph, and R. A.
Buhrman, Time-domain measurements of nanomagnet dynamics driven by spin-transfer
torques, Science, vol. 307, Jan. 2005.
[3] M. R. Pufall, W. H. Rippard, S. Kaka, T. J. Silva, and S. E. Russek,Frequency
modulation of spin-transfer oscillators, Appl. Phys. Lett., vol. 86, p. 082506, 02, 2005.
[4] I.Y.Oh,M.C.Shin,andC.S.Park,2.21mWlowpowerconsumption digitally controlled
spintronics oscillator (DCSO), in IEEE-IMS2013, TU1C-1, Jun. 2013, [CD ROM].
[5] S. Bonetti, P. Muduli, F. Mancoff, and J. Akerman, Spin torque oscillator frequency
versus magnetic field angle: The prospect of operation beyond 65 GHz, Appl. Phys.
Lett.,vol. 94, p. 102507, 2009.
[6] Y. Zhou, S. Bonetti, J. Persson, and J. Akerman, Capacitance enhaced synchronization
of pairs of spin-transfer oscillators, IEEE Trans.Magnetics, vol. 45, no. 6, pp. 24212423,
Jun. 2009.
[7] F. Jonietz, S. Muhlbauer, C. Pfleiderer, A. Neubauer, W. Munzer, A. Bauer, T. Adams, R.
Georgii, P. Boni, R. A. Duine, K. Everschor, M.Garst, and A. Rosch, Spin transfer torques
in MnSi at ultralow current densities, Science, vol. 330, no. 6011, pp. 16481651, Dec.
2010.
[8] L. Fanori and P. Andreani, A 2.5-to-3.3 GHz CMOS class-D VCO, in Proc. ISSCC13,
Feb. 20, 2013, [CD ROM].
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 24 METS school of Engg, Mala
[9] M. Hsu, T. Han, and P. Lee, Design of sub-1 mW Q-enhancement CMOS LC VCO with
body-biased technique, in Proc. World Congress Eng. (WCE13), London, U.K., Jul. 35,
2013, pp. 11241126.
[10] A. M. Deac, A. Fukushima, H. Kubota, H. Maehara, Y. Suzuki, S. Yuasa, Y. Nagamine,
K. Tsunekawa, D. D. Djayaprawira, and N. Watanabe, Bias-driven high-power microwave
emission from MgO-based tunnel magnetoresistance devices, Nature Phys., vol. 4,
pp. 803809, Oct. 2008.
[11] J. Persson, Y. Zhou, and J. Akerman, Phase-locked spin torque oscillators: Impact of
device variablility and time delay, J. Appl. Phys.,vol. 101, p. 09A503, 2007.
-
Seminar Report 2015 Wireless Spintronics Modulation
Dept. of Electronics and Communication 25 METS school of Engg, Mala