Surface Acoustic Wave Filters (eBook)

Front cover 1
Surface Acoustic Wave Filters 4
Copyright page 5
Contents 6
Preface 12
Foreword to second edition 16
Foreword to previous edition (1991) 18
Chapter 1 Basic survey 20
1.1 Acoustic waves in solids 21
1.2 Propagation effects and materials 26
1.3 Basic properties of Interdigital Transducers 28
1.3.1 Transducer reflectivity and the triple-transit signal 28
1.3.2 Non-reflective transducers: delta-function model 30
1.4 Apodization and transversal filtering 37
1.5 Correlation and signal processing 41
1.6 Wireless interrogation: sensors and tags 43
1.7 Resonators and low-loss filters 44
1.7.1 Gratings and resonators 45
1.7.2 Low-loss filters for RF 46
1.7.3 Low-loss filters for IF 48
1.7.4 Performance of bandpass filters 50
1.8 Summary of devices and applications 52
Chapter 2 Acoustic waves in elastic solids 57
2.1 Elasticity in anisotropic materials 57
2.1.1 Non-piezoelectric materials 58
2.1.2 Piezoelectric materials 60
2.2 Waves in isotropic materials 62
2.2.1 Plane waves 63
2.2.2 Rayleigh waves in a half-space 65
2.2.3 Shear-horizontal waves in a half-space 70
2.2.4 Waves in a layered half-space 70
2.2.5 Waves in a parallel-sided plate 74
2.3 Waves in anisotropic materials 76
2.3.1 Plane waves in an infinite medium 76
2.3.2 Theory for a piezoelectric half-space 77
2.3.3 Surface-wave solutions 79
2.3.4 Other solutions 82
2.3.5 Surface waves in layered substrates: perturbation theory 82
Chapter 3 Electrical excitation at a plane surface 87
3.1 Electrostatic case 87
3.2 Piezoelectric half-space 91
3.3 Some properties of the effective permittivity 94
3.4 Green's function 98
3.5 Other applications of the effective permittivity 101
Chapter 4 Propagation effects and materials 106
4.1 Diffraction and beam steering 106
4.1.1 Formulation using angular spectrum of plane waves 107
4.1.2 Beam steering in the near field 109
4.1.3 Minimal-diffraction orientations 110
4.1.4 Diffracted field in the parabolic approximation: scaling 111
4.1.5 Two-transducer devices 114
4.2 Propagation loss and non-linear effects 119
4.3 Temperature effects and velocity errors 120
4.4 Materials for surface-wave devices 123
4.4.1 Orientation: Euler angles 123
4.4.2 Single-crystal materials 124
4.4.3 Thin films 127
Chapter 5 Non-reflective transducers 133
5.1 Analysis for a general array of electrodes 134
5.1.1 The quasi-static approximation 134
5.1.2 Electrostatic equations and charge superposition 137
5.1.3 Current entering one electrode 141
5.1.4 Evaluation of the acoustic potential 142
5.2 Quasi-static analysis of transducers 144
5.2.1 Launching transducer 144
5.2.2 Transducer admittance 146
5.2.3 Receiving transducer 147
5.3 Summary and P-matrix formulation 149
5.4 Transducers with regular electrodes: element factor 153
5.5 Admittance of uniform transducers 158
5.5.1 Acoustic conductance and susceptance 159
5.5.2 Capacitance 162
5.5.3 Comparative performance 163
5.6 Two-transducer devices 164
5.6.1 Device using unapodized transducers 165
5.6.2 Device using an apodized transducer 168
5.6.3 Admittance of apodized transducers 171
5.6.4 Two-transducer device using a multistrip coupler 173
Chapter 6 Bandpass filtering using non-reflective transducers 176
6.1 Basic properties of uniform transducers 177
6.2 Apodized transducer as a transversal filter 180
6.3 Design of transversal filters 188
6.3.1 Use of window functions 188
6.3.2 Optimized design: the Remez algorithm 192
6.3.3 Withdrawal weighting 194
6.4 Filter design and performance 196
Chapter 7 Correlators for pulse compression radar and communications 202
7.1 Pulse compression radar 203
7.2 Chirp waveforms 206
7.2.1 Waveform characteristics 206
7.2.2 Weighting of linear-chirp filters 211
7.3 Interdigital chirp transducers and filters 215
7.3.1 Chirp transducer analysis 216
7.3.2 Transducer design 221
7.3.3 Filter design and performance 223
7.4 Reflective array compressors 227
7.5 Doppler effects and spectral analysis 229
7.6 Correlation in spread-spectrum communications 231
7.6.1 Principles of spread-spectrum systems 231
7.6.2 Linear matched filters for PSK 233
7.6.3 Non-linear convolvers 234
Chapter 8 Reflective gratings and transducers 244
8.1 Reflective array method for gratings and transducers 245
8.1.1 Infinite-length grating 245
8.1.2 Finite-length grating 248
8.1.3 Transducer with regular electrodes 250
8.1.4 Reflectivity and velocity for single-electrode transducers 252
8.2 Coupling of Modes (COM) Equations 257
8.2.1 Derivation of equations 257
8.2.2 General solution for a uniform transducer 261
8.2.3 The Natural SPUDT effect in single-electrode transducers 267
8.3 Numerical evaluation of COM parameters 270
8.3.1 Theoretical methods for periodic structures 270
8.3.2 Coupled-mode parameters from band edge frequencies 275
Chapter 9 Unidirectional transducers and their application to bandpass filtering 282
9.1 General considerations 283
9.2 DART mechanism and analysis 285
9.3 Bandpass filtering using DARTs 293
9.4 Other SPUDT structures and analysis for parameters 297
9.5 Other SPUDT filters 301
9.6 Other low-loss techniques 305
Chapter 10 Waveguides and transversely coupled resonator filters 312
10.1 Basic strip waveguides 313
10.2 Waveguide modes in interdigital devices 318
10.3 Analysis for general waveguides 321
10.4 Transversely-Coupled Resonator (TCR) filter 323
10.5 Unbound waveguide modes 328
10.6 Waveguides including electrode reflectivity 331
Chapter 11 Resonators and resonator filters 336
11.1 Resonator types 337
11.1.1 Gratings and cavities 337
11.1.2 Single-port resonator 341
11.1.3 Two-port resonator 345
11.1.4 Single-electrode transducer as resonator 349
11.2 Surface-wave oscillators 351
11.3 Impedance Element Filters 354
11.4 Leaky waves 359
11.4.1 Leaky waves and surface-skimming bulk waves 359
11.4.2 Leaky waves in lithium tantalate 361
11.4.3 Coupled-mode analysis of gratings and transducers 365
11.4.4 Other leaky waves 370
11.5 Longitudinally-Coupled Resonator (LCR) filters 371
Appendix A: Fourier transforms and linear filters 378
A.1 Fourier transforms 378
A.2 Linear filters 382
A.3 Matched filtering 385
A.4 Non-uniform sampling 388
A.5 Some properties of bandpass waveforms 390
A.6 Hilbert transforms 395
Appendix B: Reciprocity 397
B.1 General relation for a mechanically free surface 397
B.2 Reciprocity for two-terminal transducers 398
B.3 Symmetry of the green's function 402
B.4 Reciprocity for surface excitation of a half-space 403
B.5 Reciprocity for surface-wave transducers 403
B.6 Surface-wave generation 406
Appendix C: Elemental charge density for regular electrodes 409
C.1 Some properties of legendre functions 409
C.2 Elemental charge density 412
C.3 Net charges on electrodes 414
Appendix D: P-matrix relations 416
D.1 General relations 416
D.2 Cascading formulae 419
Appendix E: Electrical loading in an array of regular electrodes 428
E.1 General solution for low frequencies 428
E.2 Propagation outside the stop band 433
E.3 Stop bands 436
E.4 Theory of the multistrip coupler 440
Index 442
A 442
B 442
C 443
D 443
E 444
F 444
G 444
H 444
I 444
K 444
L 444
M 445
N 445
O 445
P 445
Q 446
R 446
S 446
T 447
U 447
V 447
W 447
Z 448