Surface acoustic wave filters : with applications to electronic communications and signal processing 2nd ed

CONTENTS Preface xi Foreword to second edition xv Foreword to previous edition (1991) xvii Chapter 1 Basic survey 1 1.1 Acoustic waves in solids 2 1.2 Propagation effects and materials 7 1.3 Basic properties of Interdigital Transducers 9 1.3.1 Transducer reflectivity and the triple-transit signal 9 1.3.2 Non-reflective transducers: delta-function model 11 1.4 Apodization and transversal filtering 18 1.5 Correlation and signal processing 22 1.6 Wireless interrogation: sensors and tags 24 1.7 Resonators and low-loss filters 25 1.7.1 Gratings and resonators 26 1.7.2 Low-loss filters for RF 27 1.7.3 Low-loss filters for IF 29 1.7.4 Performance of bandpass filters 31 1.8 Summary of devices and applications 33 Chapter 2 Acoustic waves in elastic solids 38 2.1 Elasticity in anisotropic materials 38 2.1.1 Non-piezoelectric materials 39 2.1.2 Piezoelectric materials 41 2.2 Waves in isotropic materials 43 2.2.1 Plane waves 44 2.2.2 Rayleigh waves in a half-space 46 2.2.3 Shear-horizontal waves in a half-space 51 v vi Contents 2.2.4 Waves in a layered half-space 51 2.2.5 Waves in a parallel-sided plate 55 2.3 Waves in anisotropic materials 57 2.3.1 Plane waves in an infinite medium 57 2.3.2 Theory for a piezoelectric half-space 58 2.3.3 Surface-wave solutions 60 2.3.4 Other solutions 63 2.3.5 Surface waves in layered substrates: perturbation theory 65 Chapter 3 Electrical excitation at a plane surface 68 3.1 Electrostatic case 68 3.2 Piezoelectric half-space 72 3.3 Some properties of the effective permittivity 75 3.4 Green’s function 79 3.5 Other applications of the effective permittivity 82 Chapter 4 Propagation effects and materials 87 4.1 Diffraction and beam steering 87 4.1.1 Formulation using angular spectrum of plane waves 88 4.1.2 Beam steering in the near field 90 4.1.3 Minimal-diffraction orientations 91 4.1.4 Diffracted field in the parabolic approximation: scaling 92 4.1.5 Two-transducer devices 95 4.2 Propagation loss and non-linear effects 100 4.3 Temperature effects and velocity errors 101 4.4 Materials for surface-wave devices 104 4.4.1 Orientation: Euler angles 104 4.4.2 Single-crystal materials 105 4.4.3 Thin films 108 Chapter 5 Non-reflective transducers 114 5.1 Analysis for a general array of electrodes 115 5.1.1 The quasi-static approximation 115 5.1.2 Electrostatic equations and charge superposition 118 5.1.3 Current entering one electrode 122 5.1.4 Evaluation of the acoustic potential 123 5.2 Quasi-static analysis of transducers 125 5.2.1 Launching transducer 125 5.2.2 Transducer admittance 127 5.2.3 Receiving transducer 128 5.3 Summary and P-matrix formulation 130 Contents vii 5.4 Transducers with regular electrodes: element factor 134 5.5 Admittance of uniform transducers 139 5.5.1 Acoustic conductance and susceptance 140 5.5.2 Capacitance 143 5.5.3 Comparative performance 144 5.6 Two-transducer devices 145 5.6.1 Device using unapodized transducers 146 5.6.2 Device using an apodized transducer 149 5.6.3 Admittance of apodized transducers 152 5.6.4 Two-transducer device using a multistrip coupler 154 Chapter 6 Bandpass filtering using non-reflective transducers 157 6.1 Basic properties of uniform transducers 158 6.2 Apodized transducer as a transversal filter 161 6.3 Design of transversal filters 169 6.3.1 Use of window functions 169 6.3.2 Optimized design: the Remez algorithm 173 6.3.3 Withdrawal weighting 175 6.4 Filter design and performance 177 Chapter 7 Correlators for pulse compression radar and communications 183 7.1 Pulse compression radar 184 7.2 Chirp waveforms 187 7.2.1 Waveform characteristics 187 7.2.2 Weighting of linear-chirp filters 192 7.3 Interdigital chirp transducers and filters 196 7.3.1 Chirp transducer analysis 197 7.3.2 Transducer design 202 7.3.3 Filter design and performance 204 7.4 Reflective array compressors 208 7.5 Doppler effects and spectral analysis 210 7.6 Correlation in spread-spectrum communications 212 7.6.1 Principles of spread-spectrum systems 212 7.6.2 Linear matched filters for PSK 214 7.6.3 Non-linear convolvers 215 Chapter 8 Reflective gratings and transducers 225 8.1 Reflective array method for gratings and transducers 226 8.1.1 Infinite-length grating 226 viii Contents 8.1.2 Finite-length grating 229 8.1.3 Transducer with regular electrodes 231 8.1.4 Reflectivity and velocity for single-electrode transducers 233 8.2 Coupling of Modes (COM) Equations 238 8.2.1 Derivation of equations 238 8.2.2 General solution for a uniform transducer 242 8.2.3 The Natural SPUDT effect in single-electrode transducers 248 8.3 Numerical evaluation of COM parameters 251 8.3.1 Theoretical methods for periodic structures 251 8.3.2 Coupled-mode parameters from band edge frequencies 256 Chapter 9 Unidirectional transducers and their application to bandpass filtering 263 9.1 General considerations 264 9.2 DART mechanism and analysis 266 9.3 Bandpass filtering using DARTs 274 9.4 Other SPUDT structures and analysis for parameters 278 9.5 Other SPUDT filters 282 9.6 Other low-loss techniques 286 Chapter 10 Waveguides and transversely coupled resonator filters 293 10.1 Basic strip waveguides 294 10.2 Waveguide modes in interdigital devices 299 10.3 Analysis for general waveguides 302 10.4 Transversely-Coupled Resonator (TCR) filter 304 10.5 Unbound waveguide modes 309 10.6 Waveguides including electrode reflectivity 312 Chapter 11 Resonators and resonator filters 317 11.1 Resonator types 318 11.1.1 Gratings and cavities 318 11.1.2 Single-port resonator 322 11.1.3 Two-port resonator 326 11.1.4 Single-electrode transducer as resonator 330 11.2 Surface-wave oscillators 332 11.3 Impedance Element Filters 335 11.4 Leaky waves 340 11.4.1 Leaky waves and surface-skimming bulk waves 340 Contents ix 11.4.2 Leaky waves in lithium tantalate 342 11.4.3 Coupled-mode analysis of gratings and transducers 346 11.4.4 Other leaky waves 351 11.5 Longitudinally-Coupled Resonator (LCR) filters 352 Appendix A Fourier transforms and linear filters 359 A.1 Fourier transforms 359 A.2 Linear filters 363 A.3 Matched filtering 366 A.4 Non-uniform sampling 369 A.5 Some properties of bandpass waveforms 371 A.6 Hilbert transforms 376 Appendix B Reciprocity 378 B.1 General relation for a mechanically free surface 378 B.2 Reciprocity for two-terminal transducers 379 B.3 Symmetry of the green’s function 383 B.4 Reciprocity for surface excitation of a half-space 384 B.5 Reciprocity for surface-wave transducers 384 B.6 Surface-wave generation 387 Appendix C Elemental charge density for regular electrodes 390 C.1 Some properties of legendre functions 390 C.2 Elemental charge density 393 C.3 Net charges on electrodes 395 Appendix D P-matrix relations 397 D.1 General relations 397 D.2 Cascading formulae 400 Appendix E Electrical loading in an array of regular electrodes 409 E.1 General solution for low frequencies 409 E.2 Propagation outside the stop band 414 E.3 Stop bands 417 E.4 Theory of the multistrip coupler 421 Index 423