DESIGN AND FABRICATION OF LOW PHASE ERROR SINGULAR PHASE BITS FOR MEMS PHASE SHIFTER ON HRS ANESH K SHARMA 1 , ASHU K GAUTAM 2 , ASUDEB DUTTA 3 & S G SINGH 4 1,2 Directorate of Radar Seekers, Research Centre Imarat, Hyderabad, Andhra Pradesh, India 1,3,4 Indian Institute of Technology Hyderabad, Andhra Pradesh, India ABSTRACT The paper presents the design, fabrication and measurement of the MEMS based singular phase bits in Ku band for phase shifter development. The Phase Shifter bits have been designed in CPW configuration. The development architecture is based on the hybrid approach of the switched and loaded line topologies. All the switches have been monolithically manufactured on the 200 µm high resistivity silicon substrate using 4” diameter wafers. The three bits i.e. 180 o , 90° and 45° are realized through switched microstrip lines using series ohmic MEMS switches whereas the two other bits i.e. 22.5° and 11.25° consist of microstrip line sections loaded by ohmic MEMS switch in shunt mode. Individual bits have been fabricated and evaluated for RF performance. The insertion loss from 0.5dB to 1.5dB across all five bits has been measured. A very low phase error with in ±2 o has been achieved. These singular phase bits can be implemented to develop an integrated 5-bit phase shifter for radar applications. KEYWORDS: Insertion Loss, Switched Line, Loaded Line, Phase Shifter, Phase Error INTRODUCTION Micro Electro Mechanical Systems (MEMS) are a highly innovative alternative to solid state technologies for the realization of RF MEMS since it offers low power consumption, improved RF performance, high isolation and linearity, high miniaturization and reduced costs [1]. The commonality with VLSI technology has been credited to a large extent for the rapid dissemination in the various potential applications. RF MEMS devices are finding direct applications in the circuit or in Sub systems. RF MEMS components like variable capacitors and low loss switches have been proven and the same can be extended to an important device like phase shifter for critical applications [2]. The study and development of phase shifters have gained lot of significance as these are the crucial components in the phased array antenna systems. MEMS phase shifters have been developed for its inherent advantages over other electronic phase shifters. The conventional phase shifters of pin diode, ferrite and MMICs suffer from high insertion loss and dc power consumption, weight, low bandwidth and non-linearity etc. In addition MEMS can be integrated straight forwardly into RF sub-modules to achieve a higher degree of functionality. RF Switch exhibits excellent RF properties such as low insertion loss, low power consumption, high isolation and linearity making this an integral part of the phase shifter circuit [3-4]. The electrostatic force is used for the device operation and the circuits require no quiescent current thus dissipate very negligible power. A 3-D full wave approach has been used for EM simulation. This paper is a continuation of the MEMS phase shifter development effort with a particular emphasis on low phase error. DESIGN AND SIMULATION Different topologies such as switched [5-7] and loaded line, reflection-type and distributed MEMS transmission lines (DMTL) have been reported in literature. The most convenient depends on the specific requirements, such as frequency range, space occupation and loss, etc. Typically the loaded line topology is convenient in terms of insertion loss International Journal of Electrical and Electronics Engineering Research (IJEEER) ISSN 2250-155X Vol. 3, Issue 3, Aug 2013, 177-186 © TJPRC Pvt. Ltd.