RF MEMS Switches and Integrated Switching Circuits (eBook)

Preface 7
Contents 9
1 Introduction 11
1.1 RF MEMS Switches 11
1.2 Capacitive Shunt Switches 15
1.2.1 Reliability of Capacitive Switches 16
1.2.2 Power Handling of Capacitive Switches 16
1.2.3 Degradation of Down-State Capacitance 17
1.3 Coplanar Waveguide Transmission Lines 17
1.4 Single-Pole-Multi-Throw Switching Circuit (SPMT) 18
1.5 Electromagnetic Band Gap (EBG) Structures for RF Circuits 21
1.6 Tunable EBG Bandpass Filters and Reconfigurable Circuits 21
1.7 Capacitive Switching Bandpass Filters 23
1.8 Substrate Transfer Process 23
1.9 Surface Planarization Process 25
References 25
2 Lateral Series Switches 31
2.1 Electrical Design and Simulation 31
2.1.1 RF Circuit Design of the Lateral Switch 32
2.1.2 RF Circuit Model of the Lateral Switch 33
2.1.3 Double-Beam Lateral Switch 38
2.2 Mechanical Design and Simulation 40
2.2.1 Static Electrostatic Force 40
2.2.2 Static Restoring Force 42
2.2.3 Static Threshold Voltage 43
2.2.4 Dynamic Frequency Response 46
2.2.5 Dynamic Effective Mass 49
2.2.6 Dynamic Switching Time 51
2.2.7 Dynamic Release Time 53
2.3 Device Fabrication Processes 54
2.4 Lateral Switch Characterization 56
2.4.1 The Single-Beam Switch and the Double-Beam Switch 56
2.4.2 Cantilever Beam Design Effect 61
2.4.3 Metal Coating Effect 64
2.4.4 The Lateral Switch with a Separate Fixed Electrode 66
2.5 Mechanical Measurements 68
2.5.1 Static behavior 68
2.5.2 Dynamic Behavior 69
2.5.3 Reliability of the Lateral Switch 70
2.6 Summary 72
References 72
3 Capacitive Shunt Switches 75
3.1 Broadband DC-Contact Capacitive Switch 75
3.1.1 Electromagnetic Design and Modeling 75
3.1.2 Mechanical Design 80
3.1.3 Experimental Results and Discussions 84
3.2 DOG Switch on Low-Resistivity Silicon Substrate 87
3.3 Summary 91
References 92
4 Coplanar Waveguide Transmission Line 93
4.1 Design of the Si-Core CPW 93
4.2 Losses of the Si-Core CPW 96
4.2.1 Conductor Loss 96
4.2.2 Dielectric Loss 97
4.2.3 Radiation Loss 98
4.3 Effect of Material Properties and Fabrication Processes 99
4.3.1 Effect of Different Substrate Materials 99
4.3.2 Effect of Different Core Materials 100
4.3.3 Effect of Different Fabrication Processes 101
4.4 Experimental Results and Discussions 104
4.4.1 Comparison Between Simulation Results and Measurement Results 105
4.4.2 Effect of Geometrical Parameters 107
4.4.3 Effect of Material Properties 108
4.5 Surface-Micromachined CPW Transmission Line 112
4.5.1 Characteristic Impedance and Effective Dielectric Constant 112
4.5.2 Losses of CPW Structure 116
4.5.3 Effects of Material Properties 118
4.5.4 Effects of Metal Thickness 119
4.5.5 Experimental Results and Discussions 120
4.6 Summary 122
References 122
5 Single-Pole-Multi-Throw Switching Circuits 125
5.1 SP2T Switching Circuit 125
5.1.1 Design of the In-line SP2T Switching Circuit 125
5.1.2 Modeling and Simulation of the SP2T Switching Circuit 126
5.1.3 Different Types of SP2T Switching Circuits 129
5.2 Design of the SP3T Switching Circuit 131
5.3 Design of the SP4T Switching Circuit 133
5.4 Experimental Results and Discussions 133
5.4.1 In-line SP2T Switching Circuit 135
5.4.2 Different Designs of the SP2T Switching Circuits 137
5.4.3 SP3T Switching Circuit 138
5.4.4 SP4T Switching Circuit 141
5.5 Summary 141
References 141
6 Tunable Electromagnetic Band Gap Bandstop Filter 143
6.1 Unloaded EBG Bandstop Filter 143
6.1.1 Effects of the Unloaded Square Aperture Size 144
6.1.2 Influence of the Transverse Slot Width 145
6.1.3 Influence of the Transverse Slot Length 145
6.1.4 Modeling of the Unloaded EBG 146
6.1.5 Propagation Characteristics of the Unloaded Unit EBG 149
6.2 Loaded EBG Bandstop Filter 151
6.2.1 Effect of the Square-Etched Hole 152
6.2.2 Modeling of the Loaded EBG Structure 153
6.2.3 Propagation Characteristics of the Loaded Unit EBG 156
6.3 Experimental Results and Discussions 158
6.3.1 Unloaded EBG Bandstop Filter 158
6.3.2 Loaded EBG Bandstop Filter 159
6.4 Design of Tunable Bandstop Filter 161
6.4.1 Experimental Results and Discussions 164
6.5 Summary 167
References 168
7 Tunable Electromagnetic Bandpass Filter and Reconfigurable Circuit 169
7.1 Theory of the FabryPerot of Tunable Filter 169
7.2 Design of the EBG Circuit 171
7.2.1 Capacitively Loaded Transmission Line Circuit Analysis 172
7.3 Design of FabryPerot Tunable Bandpass Filter 174
7.3.1 Effects of the Number of EBG Structures 176
7.3.2 Effect of the Defect Length 177
7.3.3 Effects of the Slot Dimension 178
7.3.4 Effect of Propagation Characteristics 179
7.4 Experimental Results and Discussions 180
7.5 Reconfigurable Switching Filter 183
7.5.1 Unit Reconfigurable Structure and Its Modeling 185
7.5.2 Propagation Characteristics 187
7.5.3 Effects of the Bigger Slot Width 189
7.5.4 Effect of the Transverse Slot Width 190
7.5.5 Experimental Results and Discussions 192
7.6 Summary 196
References 196
8 Capacitive Switching Bandpass Filters 199
8.1 Capacitance Tuning Bandpass Filter 199
8.1.1 Design of the Capacitance Tuning Bandpass Filter 199
8.1.2 Experimental Results and Discussions 203
8.2 Inductance Tuning Bandpass Filter 203
8.2.1 Design of the Inductance Tuning Filter 203
8.2.2 Experimental Results and Discussions 210
8.3 Summary 216
References 216
9 Substrate Transfer Process 217
9.1 Design of the Substrate Transfer Process 217
9.2 Silicon and Glass Anodic Bonding 221
9.2.1 Si/Thin Film/Glass Anodic Bonding Mechanism 221
9.2.2 Preparation of Bonding Samples 223
9.2.3 Experimental Results and Discussions 224
9.3 Wafer Thinning via KOH Anisotropic Etching 226
9.3.1 Layout Design Considerations 227
9.3.2 Etching Temperature Effect 229
9.4 Shadow Mask Techniques 229
9.4.1 Design and Fabrication of the Shadow Mask 230
9.4.2 Shadow Mask Applications 232
9.5 Summary 236
References 236
10 Surface Planarization Process 239
10.1 Surface Planarization Process 239
10.2 RF Measurement and Analysis 242
10.3 Effects of Dry Releasing of Metal Bridge 245
10.3.1 Etch Rate of Photoresist 245
10.3.2 Structural Stress 248
10.3.3 Characterization of Capacitive Switch 255
10.4 Effects of Surface Roughness 256
10.4.1 Greenwood--Williamson Model 256
10.4.2 Analysis of Surface Roughness Effects 257
10.4.3 Experimental Results and Discussions 268
10.5 Summary 273
References 273
Index 275
About the Author 280