RF MEMS Based 60 GHz Variable Attenuator

This paper presents a millimeter-wave variable-attenuator realized using a lateral radio-frequency (RF) microelectromechanical systems (MEMS) capacitive type switch. The proposed variable attenuator comprises of two CPW based quadrature hybrid couplers paired with capacitive type thermally-actuated lateral MEMS switches. The voltage applied to the Chevron actuator regulates the precise mechanical movement of the contact plate and hence defines the range of attenuation. At the center frequency of 60 GHz, the attenuation monotonically varied from 4 dB to 20 dB with the applied voltage. Return loss better than 20 dB over a bandwidth of 4 GHz is achieved. The proposed fabrication process provides the ability to integrate the lateral actuators, movable plates, RF CPW lines, and the CPW hybrid coupler and other supporting structures on an SOI substrate.