saw tech presentation

8/10/2019 SAW Tech Presentation

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Background & Applications


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Motivation For SAW

Technology Frequency range from ~ 10 MHz to 3 GHz

_ Monolithic, solid state

Standard manufacturing process, similar

to IC

Provide complex signal processing

Mass produced, low cost

Void of competing technologies


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SAW Advantage


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Applications of SAW Devices

Military Was Initial Motivation

Pulse Expansion & Compression FiltersRanging

Pulse Shaping, Matched Filters,

Programmable Tapped Delay Lines,

Convolvers, Fast Hop Synthesizer

Fast Hop Synthesizer

ECCM

Direct Sequence Spread Spectrum-

Fast Frequency Hopping-

Pulse Memory Delay LineECM Jammers

Pulse Expansion and Compression

FiltersRadar Pulse Compression

Functions PerformedMilitary Applications


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High Volume Consumer Markets

Have Driven the Technology

Custom designs

Develop unique acoustic component implementations

Custom materials

Better manufacturing tolerance

Low cost, surface mount packaging


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Hand Set Shipments-World


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High Volume Applications of

SAW Devices

Wireless LANAnalog Cellular

Base StationsDigital Cordless

Telephone

TV IF FilterAnalog Cordless

Telephone

Personal Communication

SystemDigital Cellular

Consumer ApplicationsConsumer Applications


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Other Applications of

SAW Devices

Oscillators and FiltersRF Synthesizers/Analyzers

Clock Recovery FilterFiber Optic Repeater

QAM Spectral ShapingDigital Microwave

IF Filter, Filter BankSatellite Data Receiver

VSB Modulator Filters and

TVRO IF FiltersCATV/MATV Headend

Functions PerformedCommercial Applications


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SAW Cost Parameters

from: RF Monolithics


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SAW Properties

Piezoelectric substrate acoustoelectric

conversion

Small surface perturbation: 0.1-20 Angstroms

Wave is trapped to surface (~ 1-15 wavelengths)

Velocity of ~ 2,500 10,000 m/sec

Efficient transduction and wave sampling

Versatile signal processing bandpass filtering,

resonator frequency control, spread spectrum,

radar, remote sensing, others


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SAW Components

Transducers

Bidirectional

Multi-phase

Unidirectional Single Phase

Unidirectional

Reflectors

Groove Metallic

Implanted

Re-Generative

Elements

Transducers

Multistrip Couplers

Wave Guides

Beam Compressors

Convolvers

Non-linear Elements

Convolver


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Surface Wave Particle

Displacement


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Bidirectional Apodized SAW Filter

Schematic diagram of a typical bidirectional SAW filter

composed of an unweighted input transducer and anapodized transducer. The filter is composed of two

interdigital transducers (IDT).


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Electric Field Distribution

Between Transducer Fingers


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Transversal Filter


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SAW Rectangular Time

Impulse Response


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SAW Rectangular Time

Impulse Response

1 0.5 0 0.5 12

0

22

2

h1 0 t,( )

Rect 0 t,( )

11 t

h1 x t,( ) a1 cos 2 f0 t( ) Rect x t,( ):=

Rect x t,( ) if min x( ) t max x( ) 1, 0,( ):=


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IDT Frequency Domain Response

From a Rectangular Time Response

H f( ) 2Sa 2 f f0( ) 2 :=

Sa x( ) if x 0sin x( )

x, 1,:=

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 250

4030

20

10

0

dBH f( )

H f0( )

f

f0

where


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Time-Frequency Design Fundamentals


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Schematic of a Finite Impulse

Response (FIR) Filter


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SAW Models


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MODELS

Transmission Line

Uses impedance discontinuitiesto model metallized vs freespace

Impulse Response/ Superposition

Models a single element in aperiodic array

Uses superposition/convolution to

determine complete response

Does not handle reflections

Coupling of Modes

Analysis via forward and

reverse traveling waves

Models transduction and

reflection


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SAW Impulse Response

Transducer Model

Schematic representation of a SAW IDT and the fundamental wave

perturbation under the electrode pattern when driven by an impulse.


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SAW Transducer Impulse Response ModelFor a uniform sampled SAW transducer:

h(t) =A0 cos[z0t]rect(t/t)

andA0equals a constant.

Assume a delta function voltage input, v0(t) = d(t),

then V0(z) =1. Given h(t), H(z) is known and the

energy launched as a function of frequency is given

by (z) = 2 * H(z) . Then

E(z) =V02(z) * Ga(z) = 1 * Ga(z)

or

Ga(z) = 2 * H(z) 2


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SAW Transducer Impulse Response Model

Dt= 12*f0 tn=n *Dt N*Dt=t Np * Dt=t/2.where N is the total number of electrodes (half wave-

lengths) and Np is the total number of electrodepairs.

H

(z

) =A

0

N

4f0*

sin(xn)

xn

wherexn= (zz0)

z0 oNp= (ff0)

f0oNp.

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 250

40

30

20

10

0

dBH f( )

H f0( )

f

f0


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SAW Transducer Impulse Response Model

The center frequency conductance is given as

Ga(f0) =G0= 8k2f0CsWaNp2

or the frequency dependent transducer conductance is

Ga(f0) =G0 *

sin2(xn)

xn2

The transducer electrode capacitance is given as

Ce=CsWaNp

The Hilbert transform susceptance is,

Ba(z) = 1o

Ga(u)(uz)du=Ga(z) & 1/oz

where "*" indicates convolution.


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SAW Transducer Modeling


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Transmission Line Model

-SAW Reflector


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Transmission Line Model

-SAW Transducer


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S11 f( )j K f( ) sinh f( ) Ng p( )

f( ) cosh f( ) Ng p( ) j f( ) j( ) sinh f( ) Ng p( )+:=

S12 f( )1( )Ng f( )

f( ) cosh f( ) Ng p( ) j f( ) j( ) sinh f( ) Ng p( )+:=

1.45 .108 1.46 .108 1.47 .108 1.48 .108 1.49 .108 1.5.108 1.51 .108 1.52 .108 1.53 .108 1.54 .108 1.55 .1080

0.5

1

0

1

S12 f i( )

S11 f i( )

fi

SAW Coupling of Modes

Model


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Apodized SAW Transducer Implementations


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Schematic of a Finite Impulse

Response (FIR) Filter


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Apodized SAW Analysis

(20)h(t) =Si=1

I

hi(t)

and

(21)H(z) =Si=1

I

Hi(z) =Si=1

I

t/2

t/2

hi(t)ejztdt

Figure 2. Schematic diagram of a typical SAW filter composed of one

unweighted interdigital transducer (IDT) and an apodized transducer.


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SAW Amplitude Beam Profile as a Function of Frequency

0.25 0 0.25 0.5 0.75 10.5

0.4

0.3

0.2

0.1

0

0.1

0.2

0.3

0.4

0.5

Center frequency (f0)

0.95*f0

0.93*f0

0.86*f0

Wave Amp. vs Beam Position vs. Frequency

Relative SAW Amplitude

NormalizedBeamPosition(x/Wa)

0.75 0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 1.2550

40

30

20

10

0

Conductance

Frequency Response

Ideal H(f) and Conductance: ACOS Fcn.

Normaliz ed Freque ncy (f/f 0)

dB


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20 to 1 Tap Quartz Ang.=3020 to 1 Tap Quartz Ang.=30


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Acoustic Conductance vs

Apodization Technique


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Filter Analysis Model


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Transducer Time Response


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Low Shape Factor

Slant-Apodized Transducer Filter

Passband Response Wideband Response


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VSB Filter for CATV - Sawtek


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Sonet SAW Filter - Sawtek


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Real Time SAW Fourier Chirp Transform

Sawtek, Inc.


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SAW Coded Transducer

Data

ClockPulseGenerator

-1 1 -1 1 -1-1 1-1

CodedTransducer

SAW Waveform

InputTransducer

SAW Coded Transducer


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Electrical Network Effects


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Electrical Network Effects

SAW equivalent circuit model which includes the

generator, parasitic resistance, and a tuning inductor

and)( oa

so

fGWaCo

rQ =

where Gg is the generator conductance.

g

sog

GWaCQ =


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Electrical Matching EffectsThe effects of the electrical network can be demonstrated by assuming a

simple parallel matching inductor, and no parasitic resistance. It will be

assumed that the transducer can be exactly matched to the real load

impedance. The transfer function, ignoring the Hilbert transform

susceptance can be written as

where .He(z) = Gg/(zoCe)

bGa(f0)z0Ce

+Ga(f)Ga(f0)+j[

zz0

z0z]

b=Gg/Ga(f0)

Figure 8 shows a series of plots of the effects of the electrical network

transfer function as a function of Q. At center frequency, half the voltage is

on the SAW conductance, which corresponds to the -6 dB level. Off center

frequency, the voltage increases which causes a loss in sidelobe rejection.


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Qr 1:=

0.6 0.8 1 1.2 1.425

20

15

10

5

0Ideal and Complete Matched Response

Normalized Frequency

dB Sa x f Qr ,( )( )( )

dB Ht f Qr ,( )( )

ff0

Qr 5:=

0.6 0.8 1 1.2 1.425

20

15

10

5

0Ideal and Complete Matched Response

Normalized Frequency

dB Sa x f Qr ,( )( )( )

dB Ht f Qr ,( )( )

f

f0

Matched Transducer Response


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Materials


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Materials Single crystal substrates

Quartz, Niobates, Tantalates

Piezoelectric Films ZnO AlN

Other Substrates Glass

Si GaAs Diamond LGS, LGN, LGT


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SAW Filter Process

Trim (if necessary)

Dice

Clean

Final Trim

Package


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Fabrication (3) Electrode Widths

From: Siemens


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MATERIAL CONSIDERATIONS

SAW Material Parameters

16200.85-140OO 1110Bi12GeO 20

39775.3-72X128Rotated YLiNbO3(128)

34884.6-94ZYLiNbO3(YZ)

32300.74-35ZYLiTaO3(YZ)

31570.160X+45.75Rotated YQuartz (ST)

32090.25-32X-20Rotated YQuartz (HC)

V(m/S)k2(%)TC (ppm/C)PropertyCutMaterial

For YZ LiNbO3

For YZ LiNbO3: first letter Cut direction

2nd letter Prop. direction

Crystal Planes & Directions

3D Structure

1) intercepts: 2a, 4b, 3c

2) reciprocal: 1/2, 1/4, 1/3

3) Miller indices: (6, 3, 4)

smallest integers

SAW Filt I ti L


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SAW Filter Insertion Loss vs

Fractional Bandwidth


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Computer Generated Filter Layout


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Mask Structure Device Features


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Improvement

in PowerDurability of

SAW Filters

T.Nishihara, H.Uchishiba, T.Matsuda, O.Ikata, &Y.Satoh

Fujitsu Laboratories Ltd.

Akashi, Japan

386 1995 IEEE Ultrasonics Symposium


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Lifetime Dependence on Input Power for

3-Layered Films with Different

Intermediate Layers

Nishihara, et. al.


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SAW Transversely Coupled Coupled Resonator

Regions 1 and 11 are free surface; regions 2 and 10 are bus bars;

regions 3, 5, 7 and 9 are gaps; regions 4 and 8 are the gratings; and

region 6 is the coupling bar. Each region can have different waveguide

properties.

l i Al hi k f Q


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Velocity vs Al Thickness for Quartz

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04

3100

3110

3120

3130

3140

3150

3160S T-Quartz Grating, Gap and Metal Velocities

h/lambda

Velocity(m/sec)

Velocity versus normalized film thickness . The lower trace is the

grating velocity, the center trace is the gap region velocity, and the

upper trace is the solid metal velocity.

TCR P l S i M t l Thi k


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0 0.5 1 1.5 2 2.5 3 3.5 4

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1Beam width= 4 to 14 lam0, Step= 2 lam0, CW=1

Metal thickness, % of h/l

PoleSpacing,

MHz

TCR Pole Spacing vs Metal Thickness

Figure 4. Pole spacing vs normalized metal fim thickness for a coupling width of 1. Beam

width is stepped in 2 increments with 4 wavelengths wide for largest pole spacing and 14

for smallest pole spacing. The crosses mark the maximum pole spacing. The open circles

are measured data of the pole spacing at a given metal thickness.


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01

23

4

0

0.5

1

1.5

2

0

0.5

1

1.5

x 10-3

Delv/v Beam width=6

Coupling width

(h/lambda in %)

ModeSeperation(delf/f0)

Plot of the normalized mode spacing vs coupling width vs

normalized film thickness for a transducer aperture of 6

wavelengths.


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Effect of Metal Thickness for Reflector

From: S.Richie


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Reactive Ion Etching of Quartz

Test#5: PR/Al mask, 125W, 5SCCM C2F6, P=32 microns, 45 min, graphite plate


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Packaging{ Currently most high volume packaging use

surface mount

{Metal packages are primarily militaryapplications

{Issues:~Extremely low cost~Hermeticity~Sealing~RF compatibility~Volume (footprint)~Internal matching

{RF problems in packages is of importance


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Assembly

process forflip-chip

SAW filters

Miniaturized SAW Filters Using aFlip-Chip Technique

H.Yatsuda, T.Horishima, T.Eimura

& T.Ochwa

1994 Ultrasonics Symposium - 159


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GSM IF Filters: Evolution of

Package Size

Source: Siemens


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Second Order Effects


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Approximate Triple Transit

Analysis

Simple Triple Transit Level Analysis


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Simple Triple Transit Level Analysis( (

( )

( )

( )

( )( )( )( ) ( ) ( ) ( )

dBILdBILTTEP

P

PILPILILP

PP

RP

PP

RP

R

PR

R

RP

R

PR

PP

o

oo

o

o

inout

10forvalid62log10

41

41

21

21

21

21

21

21

21

21

21

21

2

1

2

1

2

1

21

todue#[email protected]

21

21


21


21

21

1)(port#[email protected]

21

21:responseMain.1

2

2

2

21122

11122

1122

222

2

112

1

111

1

21

21

>+==

=

=

==

=

=

=

=

=

SAW V l i P i


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SAW Velocity vs Propagation

Angle ST Quartz


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SAW Propagation SimulationSAW Propagation Simulation20 Tap to 1 Tap Apodized Transducer on Quartz, PFA=3020 Tap to 1 Tap Apodized Transducer on Quartz, PFA=30oo

Beam steering-group velocity

is steering wave upward


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Slanted SAWFilter Analysis

With and

WithoutDiffraction -

Theoretical

From: S. Knapp PhD thesis


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Slanted SAWFilter Analysis

With

Diffraction Predicted and

Experimental

From: S. Knapp PhD thesis


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BAW Temperature Coefficient of

Frequency

pcv

hvv

f

vfhh

h

m

mmm

mm

=

==

===

=

2

2;2

knessblank thiccystalBAW


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Frequency

pc

dTdv

v

dT

dh

hdt

dv

vdT

df

f

fvh

dT

dh

h

v

dT

dv

hdT

df

dT

hv

d

dT

df

m

m

m

m

m

m

mm

mmm

m

m

in1Expand

111

then,12bysidesbothMultiply

22

1

2

2

=

=

=

=


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Frequency

+

=

=

=

=

=

dT

dh

hdT

d

dT

dc

cdT

df

f

dTd

dTdc

cdTdv

v

cv

dT

dc

cdT

dv

dT

cd

dT

dv

m

m

m

m

m

m

m

11

2

11

2

11

11211

then,1bysidesbothMultiply

2

11

2

1

:Expand

23

T bl f M i l C f LGS LGN LGT


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Table of Material Constants for LGS, LGN, LGT

Ref. Temp=25oC LGT LGN LGS

RT(x10^10)

TC1(x10^-6)

TC2(x10^-9)

RT(x10^10)

TC1(x10^-6)

TC2(x10^-9)

RT(x10^10)

TC1(x10^-6)

TC2(x10^-9)

C11 (N/m) 18.852 -78.239 -273.644 19.299 -56.335 -5.745 18.849 -43.908 -8.183C66 (N/m) 4.032 -43.633 -901.446 4.116 15.247 -176.812 4.221 -22.432 -64.402C33 (N/m) 26.180 -102.255 -107.715 26.465 -114.656 90.724 26.168 -91.904 -491.305C44 (N/m) 5.110 21.653 -11.987 4.956 -14.137 -379.544 5.371 -44.046 127.130C14 (N/m) 1.351 -359.568 1604.810 1.485 -478.918 -1943.861 1.415 -309.099 261.107C13 (N/m) 10.336 -111.390 -557.682 10.225 -31.269 947.985 9.688 -61.952 -1446.007EXPANSION-Y 0.000 6.087 4.736 0.000 6.673 -4.135 0.000 5.630 5.979EXPANSION-Z 0.000 3.827 5.030 0.000 5.060 0.000 0.000 4.079 4.577

DENSITY (g/m^3) 6150.400 -16.016 -14.502 6028.900 -18.410 9.010 5739.200 -15.340 -13.460Piezo e11 -0.456 -22.800 -981.000 -0.452 99.300 456.000 -0.402 329.000 199.000Piezo e14 0.094 1587.000 2293.000 0.061 2306.000 5053.000 0.130 -342.000 2287.000Relative epsilon 11 18.271 -65.480 -35.960 20.089 171.400 -290.500 19.620 322.900 -1073.000Relative epsilon 33 78.950 -1417.000 -16.100 79.335 -1596.000 -2935.000 49.410 -737.100 543.900

Room temperature is 25oC.

Reference temperature is 25o

C for all measurements.All values are with respect to the IEEE 176-1949 (R1971)

Standard on Piezoelectricity

BAW Temperature Coefficient of Frequency


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p q y

versus Propagation Angle


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RF P b St ti f D t A i iti


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RF Probe Station for Data Acquisition


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System Application Driven


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System Application Driven

Primary Frequency Range70 MHz - 2.5 GHz

Fractional Bandwidths


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Four Principal Saw Properties

_ Transduction

_ Reflection

_ Re-Generation _ Non-Linearities

All SAW devices implement or exhibit oneor more of these fundamentalacoustic/electrical properties


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Technology IssuesRF F il ters

v Low Loss


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Filter Using Unidirectional

Transducers (UDT): 3-Phase

Three Phase UDT Low Loss Filter Results


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Wide Band

Filter

Response

Narrowband

Filter

Response


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Technological Advances

Semi-Resonant Devices

8 Single Phase Unidirectional Transducers (SPUDT)

8 Natural SPUDT (NSPUDT)

8 Single Pole Resonators

8 Multipole Resonators

8 Transverse Coupled Resonators

8 Reflector structures

8 Multitransducer structures


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Schematic representation of a

SPUDT. The transducer is

composed of a transduction and

reflection structure. The reflecting

structure may be incorporated into

the transduction structure or can

be superimposed onto the

transduction structure. The

reflector can be made by mass

loading of metal or dielectric

material. (Malocha, 1993)

SPUDT Schematic Representation

SPUDT Macroscopic Reflection


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p

Figure 5 Macroscopic Reflection. The figure above illustrates how a wave

propagating under a transducer might be reflected. Note that the incident forward

waves amplitude is diminished as it propagates under the array of electrodes and

that the reflected waves amplitude grows as it propagates beneath the array.

SPUDT Advantages


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SPUDT Advantages

Low-loss SAW Filters (~3-15dB)

Reduced triple transit

Low pass band amplitude ripple

Small group delay distortion

Small size compared to multi-transducer

approaches

Simple matching circuits (1-2 reactive elements)

Relatively insensitive to matching elementvariations

Easy to fabricate - single level metal

SPUDT Four Basic Unit Cells


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SPUDT Four Basic Unit Cells

Abbott 1989

A) Transduction and reflector, B) Transduction and no

reflector, C) Reflector without transduction, and

D) No transduction and no reflector.

SPUDT Time Domain


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S U

SPUDT Frequency Domain


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SPUDT Frequency Domain


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Resonator Equivalent Circuits

SAW Resonator Filter


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SAW Resonator Filter

Typical SAW Resonator Measured


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Typical SAW Resonator- Measured

Resonators were designed having a center frequency

wavelength of 19.22 um.

Resonator Q~5000

118 119 120 121 122 123 124 125 126 127 128 12970

60

50

40

30

20

10

0Narrow Band S21 Graph

Frequency (MHz)

A

mplitude(dB)


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SAW Transversely Coupled

Coupled Resonator


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Ladder Circuit

Structure


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SAW Fixed Frequency Oscillator

From Sawtek, Inc.


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SAW Voltage Controlled Oscillator

with permission from Sawtek, Inc.


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SAW C d D l Li t 856 MH


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SAW Code Delay Line at 856 MHz


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RX1000 Block Diagram


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RX1000 Block Diagram

SAW Beam Width


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SAW Beam Width

Compression Convolver


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Simple SAW Film Sensor

SAW B k C d


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SAW Barker Code

Generator/Correlator

Sawtek, Inc.


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Minimum Shift Key SAW Filter


129/145

Mask Waveform Generator

Quadrature System w/ AM


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h22

SAW Modulator Filter Pulse Response Derived from Theoretical and Measured Frequency Responses

Quadrature System w/o AM


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Figure 83. Three Term Even Series SAW Modulator Filter Pulse Responses Derived from

Theoretical and Measured Frequency Responses


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SAW Multichannel Filter Bank


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SAW Multichannel Filter Bank

Permission from Sawtek, Inc.

Compressi e Recei er Technolog


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Compressive Receiver Technology


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SAW Up Chirp Dispersive


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SAW Up-Chirp Dispersive

Delay Line


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Road Vehicles- World


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Handset Vendors-World


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Wireless Users Worldwide


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Competition


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Direct Conversion Receivers Thin Film Bulk Acoustic Wave

Ceramic Filters

MEMS DSP

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