Design, fabrication and characterization of RF MEMS shunt switch for wideband operation of 3 GHz to 30 GHz

Abstract

This paper presents a novel method to obtain high isolation for a wideband RF MEMS switch. The MIM shunt capacitive switch consists of two identical beams placed in parallel over floating metals of different lengths on the signal line of a CPW. With two beams in parallel, the effective resistance and inductance of the switch is lesser than a switch with only one beam. The decrease in resistance provides higher isolation at resonant frequency while the decrease in inductance provides higher isolation at frequencies beyond resonant frequency. While the increase in insertion loss due to two beams is insignificant, there is a substantial increase in isolation over a large band of frequency. A switch with two beams with isolation greater than 30 dB and insertion loss less than 0.5 dB in the range of 3 GHz to 30 GHz is demonstrated.

Manufacturing and Testing of Radio Frequency MEMS Switches Using the Complementary Metal Oxide Semiconductor Process

“…In this work, the IL and isolation for the MSS were 0.9 dB at 41 GHz and 30 dB at 41 GHz, respectively. The AV for the MSS was 10 V. Comparing to Chae et al [ 8 ], Swarnkar et al [ 9 ], Mafinejad et al [ 10 ], Savin et al [ 12 ], Liu et al [ 15 ], Lin et al [ 16 ] and Yang et al [ 17 ], the AV for the MSS in this work is lower than that of these MSS [ 8 , 9 , 10 , 12 , 15 , 16 , 17 ]. The isolation of this work exceeds that of Mafinejad et al [ 10 ], Anuroop et al [ 11 ], Lin et al [ 16 ] and Yang et al [ 17 ].…”

“…A MSS fabricated by Chae et al [ 8 ] had an AV of 15.4 V, an isolation of 38.8 dB at 2.4 GHz and an IL of 0.23 dB at 2.4 GHz. Swarnkar et al [ 9 ] presented a MSS, which the AV was 20 V. The isolation and IL for the MSS were 30 dB at 30 GHz and 0.5 dB at 30 GHz, respectively. A MSS proposed by Mafinejad et al [ 10 ] had an AV of 18 V. The isolation for the MSS was 20 dB at 21 GHz and its IL was 1 dB at 21 dB.…”

“…The radio frequency capacitive MSS provides high isolation at resonant frequency in the off state. The resonant frequency ( ) can be expressed as [ 9 ], where is inductance of the membrane and springs and is capacitance between the membrane and the S line in the off state. The capacitance ( ) relies on the geometry of the membrane and springs.…”

“…The electrothermal actuator needed an AV of 0.3 V. The AV of electrostatic actuator was 15.4 V. The hybrid MSS isolation was 38.8 dB at 2.4 GHz. Swarnkar et al [ 9 ] employed surface micromachining to fabricate a MSS with two beams over the signal line of coplanar waveguide (CPW). The structure of two beams could reduce resistance and enhance isolation for the MSS at resonant frequency.…”

“…A MSS in this study was made using the CMOS-MEMS technology. The MSS fabricated by this technology is simpler than these MSSs [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ] fabricated by surface micromachining. The isolation of the MSS is higher than that of Lin et al [ 16 ] and Yang et al [ 17 ], and the AV of the MSS is lower than that of Lin et al [ 16 ] and Yang et al [ 17 ].…”