Circuit Modeling of Commercial Rf Mems Switch

Circuit

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Circuit modeling of commercial RF MEMS switch

using a Through-Reflect-Line calibration kit

Hye-Lim Kang, Yeonsu Lee, Sung-min Sim,

Jung-Mu Kim

Department of electronic information engineering

Chonbuk National University

Jeonju, 54896, Republic of Korea

jungmukim@jbnu.ac.kr

Moisés Espinosa-Espinosa Asociación Nacional de Normalización y Certificación del Sector Eléctrico, Mexico City, Mexico

Ignacio Llamas-Garro

Centre Tecnològic de Telecomunicacions de Catalunya, Castelldefels 08860, Spain

Abstract—— In this paper, a calibration kit for equivalent circuit modeling of commercial single-pole four-throw radio frequency micro-electro-mechanical system (SP4T RF MEMS) switch is designed and fabricated. The through-reflect-line (TRL) calibration method is adopted to design the equivalent circuit from the commercial switch with high accuracy. The designed calibration kit is fabricated using a photolithography process. The RF performance of the commercial SP4T switch is measured using a fabricated calibration kit. The equivalent circuit of the commercial switch was designed from the measured data using advanced design system (ADS) simulator.

Keywords— TRL calibration kit, RF MEMS switch, RFM circiut, Flip chip bonding

1. Introduction

Instantaneous Frequency Measurement (IFM) system, which can discriminate the frequency of unknown signals, have been used in military areas [1]. However, this system generally has a large size because a conventional IFM system usually consists of a number of discriminator [2]. A reconfigurable frequency measurement (RFM) circuit is used to reduce the size of the IFM system because it has a reconfigurable discriminator instead of a number of discriminators. Therefore, the size and weight of IFM system can be much smaller than the conventional IFM circuit system [3]. Consequently, the RFM circuit system can be utilized in the unmanned aerial vehicles (UAVs), which are deployed for military and special operation applications. Recently, a RF MEMS switch which has a number of advantages such as extremely low power consumption and high resolution is used to reconfigure a discriminator of the RFM system.

In order to design the RFM system based on commercial RF MEMS switch (Radant MEMS Inc, USA), the equivalent circuit modeling of the switch is essential to simulate the RFM circuit system. The equivalent circuit modeling of the commercial RF MEMS switch can be implemented from the equivalent circuit parameters, which are extracted by accurate measurement of the S-parameters of the switch combined with calibration kit [4]. The TRL calibration method generally is more accurate than others method and is suitably used in non-coaxial measurements such as testing fixtures, or making on-wafer measurements with probes [5].

1. DESIGN

The direct measurement of the RF MEMS switch is difficult because of the distributed nature and strong interaction of the parasitic effect. Thus, calibration kit is designed to measure RF characteristics of the RF MEMS switch. Figure 1 shows the schematic diagram of the designed TRL calibration kit to extract equivalent circuit parameters of SP4T RF MEMS switch. The width of signal line (Source 1,2,3,4 and Drain) and bias line (Gate 1,2,3, and 4) is 220 μm and 20 μm, respectively. The center of the calibration kit is mounted by commercial SP4T RF MEMS switch. The calibration kit is fabricated using gold electroplating and lift-off process. The size of the fabricated calibration

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