Ka-band RF MEMS capacitive switch with low loss, high isolation, long-term reliability and high power handling based on GaAs MMIC technology

This study presents a Ka-band radio frequency (RF) micro electro mechanical systems (MEMS) capacitive switch with low loss, high isolation, long-term reliability and high power handling based on GaAs microwave monolithic integrated circuit (MMIC) technology. In this design, a T-matching structure is employed to realise impendence matching at up-state' by modifying the dimensions of centre signal line. Thus, the reflection loss and insertion loss are improved effectively. Measurement results show that in up-state' position, the input reflection coefficient (S-11) is less than -20.4dB with the forward transmission coefficient (S-21) of better than -0.27dB at Ka-band (27-40GHz). At down-state', the switch is designed in a state of self-resonance to obtain high isolation. The measured isolation is better than 20dB over Ka-band and can reach 35dB at its self-resonant frequency of 35GHz. The measured actuation voltage is about 36V. The measured lifetime is at least 5.76x10(7) cycles. The measured power handling capability can reach up to 39dBm. The proposed compact RF MEMS capacitive switch possesses excellent performances in terms of low insertion loss, high isolation, long lifetime and high power handling capability.