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

Abstract

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 (S11) is less than −20.4 dB with the forward transmission coefficient (S21) of better than −0.27 dB at Ka-band (27–40 GHz). At ‘down-state’, the switch is designed in a state of self-resonance to obtain high isolation. The measured isolation is better than 20 dB over Ka-band and can reach 35 dB at its self-resonant frequency of 35 GHz. The measured actuation voltage is about 36 V. The measured lifetime is at least 5.76 × 107 cycles. The measured power handling capability can reach up to 39 dBm. 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.