Design and Simulation of a Miniaturized RF-MEMS Reconfigurable Microstrip Combline Band Pass Filter

Abstract

Reconfigurable bandpass filter (RBPF) is crucial in various radio frequency (RF) applications. However, the use of lumped element filters have failed to show tuneable integrated solutions with low insertion loss in the high frequency range. Most reconfigurable filter designs are faced with the challenges of narrow bandwidth, high losses, bulkiness, high voltage and high power consumption. To overcome these issues, this research undertakes to develop a miniaturized reconfigurable radio frequency micro-electro-mechanical system (RF MEMS) band-pass filter designed for wireless communication at the center frequency of 30 GHz. The filter is optimized for low insertion loss, broad bandwidth, low applied voltage, lower power consumption and high linearity. The design consists of 3rd order tapped input microstrip combline transmission lines structure integrated with in-plane tunable parallel capacitors and electrothermal actuator. The transmission lines are patterned on a silicon dioxide (Si02) of thickness 1 μm placed on a silicon (Si) substrate with the dielectric constant of ε,. = 11.9. The filter occupies chip area of 1.1 mm x 0.9 mm without the dummy substrate. The 3D structure is designed and simulated in Computer Simulator Technology (CST). The result shows the achieved inband insertion loss of less than 1 dB and the return loss better than 8 dB. The proposed reconfigurable bandpass filter can tune its center frequency with relatively constant absolute bandwidth.