| Summary: | 碩士 === 國立中正大學 === 電機工程所 === 97 === In this thesis, four microwave/millimeter wave MEMS switches using the standard CMOS technologies are analyzed, designed and fabricated. Different with the readily developed MEMS switches, the major challenge in this work is the lack of fabrication freedom due to the standard process provided by the foundries. However, to be compatible with other CMOS transceiver circuitries for ultimate system integration, there is an urgent need to study and design the CMOS MEMS switches, which motivate this thesis work.
The first circuit is a 60-GHz horizontal strip-line switch based on fixed-fixed beam structure. The on/off mechanism is using capacitively coupling. By applying the bias voltage, the fixed-fixed beam, which is the signal line, bends toward the wall caused by both electrostatic attraction and repelling force. Therefore, the required actuation voltage can be reduced. In order to prevent the biased beam directly contact to ground during the actuation, a 0.05-μm dielectric membrane is preserved between signal line and ground. Moreover, the multilayer coupling capacitors serving as DC block was constructed at ground part of strip-line so that signal will flow to ground through these capacitors when switch is off.
The second circuit is a dual-cantilever direct-contact switch. Again, the transmission medium is using horizontal strip-line. The initial state of the switch is OFF since two cantilevers are disconnected. When the switch operates at ON state, two cantilevers bends to each other to make contact by electrostatic force, even the residue street warps the cantilevers up.
The third circuit is a triple-mode SPDT switch. The initial state of the switch is OFF. By applying the proper bias voltage, the electrostatic force bends the cantilever laterally to contact one of the output ports, which can thus switch the operation mode. Three modes includes all OFF, port12 ON and port13 ON.
The last circuit is a quadro-mode SPDT switch. In this circuit, the dc bias circuitries and the microwave switch circuitries are carefully arranged on the chip layout to reduce the signal leakage. The switch operate at four modes, which are all OFF, port12 ON, port13 ON, and all ON.
|
|---|
