Sukomal Dey

Design and development of a CPW-based 5-bit switched-line phase shifter using inline metal contact MEMS series switches for 17.25 GHz transmit/receive module application

A radio frequency micro-electro-mechanical system (RF-MEMS) phase shifter based on switchable delay line concept with maximum desirable phase shift and good reliability is presented in this paper. The phase shifter is based on the switchable reference and delay line configurations with inline metal contact series switches that employs MEMS systems based on electrostatic actuation and implemented using coplanar waveguide (CPW) configuration. Electromechanical behaviour of the MEMS switch has been extensively investigated using commercially available simulation tools and validated using system level simulation. A detailed design and performance analysis of the phase shifter has been carried out as a function of various structural parameters with reference to the gold-based surface micromachining process on alumina substrate. The mechanical, electrical, transient, intermodulation distortion (IMD) and loss performance of an MEMS switch have been experimentally investigated. The individual primary phase-bits (11.25°/22.5°/45°/90°/180°) that are fundamental building blocks of a complete 5-bit phase shifter have been designed, fabricated and experimentally characterized. Furthermore, two different 5-bit switched-line phase shifters, that lead to 25% size reduction and result in marked improvement in the reliability of the complete 5-bit phase shifter with 30 V actuation voltage, have been developed. The performance comparison between two different CPW-based switched-line phase shifters have been extensively investigated and validated. The complete 5-bit phase shifter demonstrates an average insertion loss of 5.4 dB with a return loss of better than 14 dB at 17.25 GHz. The maximum phase error of 1.3° has been obtained at 17.25 GHz from these 5-bit phase shifters.

Reliability Analysis of Ku-Band 5-bit Phase Shifters Using MEMS SP4T and SPDT Switches

This work presents a Ku-band microelectromechanical systems (MEMS) based 5-bit phase shifter using dc contact single-pole-four-throw (SP4T) and single-pole-double-throw switches. The design is implemented using a coplanar waveguide transmission line. Two individual 2-bit phase shifters and one 1-bit phase shifter are cascaded to develop the complete 5-bit phase shifter. The phase shifters are fabricated on 635- μm alumina substrate using a surface micromachining process. The 5-bit phase shifter demonstrates an average insertion loss of 2.65 dB in the 13-18-GHz band with a return loss better than 22 dB and average phase error less than 0.68 ° at 17 GHz. Total area of the fabricated 5-bit phase shifter is 4.7 × 2.8 mm2. The reliability of the single-pole-single-throw and SP4T switches show more than 10 million cycles with an RF power of 0.1-2 W. Furthermore, reliability of the MEMS phase shifter is extensively investigated and presented with cold and hot switched conditions. To the best of our knowledge, this is the first reported MEMS 5-bit phase shifter in the literature that has undergone different reliability and qualification testing including 3-axis vibrations.

RF MEMS Single-Pole-Multi-Throw Switching Circuits

Radio frequency micro electromechanical system (RF MEMS) based switches are widely used in microwave and millimeter wave communication systems for their low loss, excellent linearity, low power consumption and compact size compared to other contemporary solid state devices [1]. Surface micromachining technology is typically used to develop different types of single pole multi-throw (SPMT) switches like SPST, SPDT and SP4T. MEMS series and shunt switches are extensively used in SPMT RF switches for multiband selectors, filter banks, reconfigurable antennas and phase shifter applications in transmit/receive modules.

Design, development and characterization of an x-band 5 bit DMTL phase shifter using an inline MEMS bridge and MAM capacitors

A radio frequency micro-electro-mechanical system (RF-MEMS) 5?bit phase shifter based on a distributed MEMS transmission line concept with excellent phase accuracy and good repeatability is presented in this paper. The phase shifter is built with three fixed?fixed beams; one is switchable with electrostatic actuation and the other two are fixed for a metal?air?metal (MAM) capacitor. The design is based on a coplanar waveguide (CPW) configuration using alumina substrate. Gold-based surface micromachining is used to develop the individual primary phase bits (11.25?/22.5?/45?/90?/180?), which are fundamental building blocks of the complete 5?bit phase shifter. All of the primary phase bits are cascaded together to build the complete phase shifter. Detailed design methodology and performance analysis of the unit cell phase shifter has been carried out with structural and parametric optimization using an in-line bridge and MAM capacitors. The mechanical, electrical, transient, intermodulation distortion (IMD), temperature distribution, power handling and loss performances of the MEMS bridge have been experimentally obtained and validated using simulations up to reasonable extent. A?single unit cell is able to provide 31?dB return loss, maximum insertion loss of 0.085?dB and a differential phase shift of 5.95? (at 10?GHz) over the band of interest. Furthermore, all primary phase bits are individually tested to ensure overall optimum phase shifter performance. The complete 5?bit phase shifter demonstrates an average insertion loss of 4.72?dB with return loss of better than 12?dB within 8?12?GHz using periodic placement of 62 unit cells and a maximum phase error of??3.2? has been obtained at 10?GHz. Finally, the x-band 5?bit phase shifter is compared with the present state-of-the-art. The performance of the 5?bit phase shifter when mounted inside a test jig has been experimentally investigated and the results are presented. The total area of the phase shifter is 19.4?mm2. To the best of our knowledge, this is the first reported digital distributed MEMS transmission line type RF-MEMS phase shifter that has undergone different reliability stages.

RF MEMS True-Time-Delay Phase Shifter

A radio frequency microelectromechanical system (RF MEMS)-based true-time-delay (TTD) phase shifter is one of the key components in a modern electronically steerable phased array for satellite communication, radar systems, and high precision instrumentation. The phase shifter controls the signal phase in order to steer the direction of the beam [3]. RF microelectromechanical systems (MEMS) technology provides a superior performance in terms of low loss, low power consumption, and excellent linearity compared to other technologies. MEMS-based digital phase shifters provide a large phase shift and low sensitivity to electrical noise with a high tuning ratio compared to analog versions. This chapter describes different types of TTD phase shifters utilizing MEMS switches and MEMS varactors. A gold-based surface micromachining process is used to develop different kinds of MEMS phase shifters on alumina (e r = 9.8) substrates. All phase shifters are implemented using coplanar waveguide (CPW) transmission lines and actuated by electrostatic actuations. These include the analog-type distributed MEMS transmission line (DMTL) phase shifter using push-pull actuation, a 5-bit DMTL phase shifter using MEMS bridge and a fixed capacitor, 5-bit switched line phase shifter using DC-contact MEMS switches and a 2-bit and 5-bit phase shifter using MEMS SP4T and SPDT switches. This chapter includes details on the design, development, and characterization of MEMS phase shifters. Furthermore, all experimental results are validated with a circuit analysis and full-wave EM simulation.

Fabrication and characterization of RF MEMS high isolation switch upto X-band

Design and development of a metal contact switch that employs micro electromechanical systems (MEMS) based on electrostatic actuation and implemented using a coplanar waveguide (CPW) with three switch cells is presented. The design is based on the series-shunt switch configuration. The main objective of the present design is to achieve high isolation up to 12GHz frequency (X-band). The dimensions of the MEMS switch have been optimized with finite element method based Coventor Ware software. The switch has been fabricated using gold based surface micromachining process. The mechanical response, electrical response, switching time, loss performance and Intermodulation distortions of the MEMS switch have been experimentally investigated. Return loss better than 15dB and isolation greater than 60dB have been experimentally obtained upto 12GHz from the fabricated switch.

High isolation RF MEMS SPDT switch for 60 GHz ISM band antenna routing applications

This work presents a two element antenna array using radio frequency microelectromechanical system (RF MEMS) based high isolation single-pole-double-throw (SPDT) switch at 60 GHz ISM band. The device is fabricated on 635 µm alumina substrate using surface micromachining process. SPDT switch features a measured return loss of > 15 dB, insertion loss of < 2.8 dB and isolation of > 24.6 dB over the frequency band of 55–65 GHz. Total area of the SPDT switch is 2.12 mm2. To accomplish beam switching for routing applications, two patch antenna elements are monolithically integrated with the MEMS SPDT switch. Fabricated switched beam antenna exhibits a measured return loss of > 25 dB, and 10 dB impedance bandwidth of 4.2 % at 60 GHz with 66 V of bias voltage. Total area of the device is ∼ 25 mm2.

Thermal-Piezoresistive SOI-MEMS Oscillators Based on a Fully Differential Mechanically Coupled Resonator Array for Mass Sensing Applications

A mechanically coupled array technique to enable a fully differential operation of single-crystal silicon thermal-piezoresistive resonators (TPRs) has been demonstrated to alleviate resistive feedthrough issues often seen in TPRs, therefore, featuring clear resonance behavior with decent signal-to-feedthrough ratio. The proposed thermal-piezoresistive dual-II-BARs exhibits feedthrough reduction of more than 67 dB, and no spurious mode, is found within a wide frequency span. The resonator array together with board-level sustaining circuitry also works as a thermal-piezoresistive oscillator (TPO) and demonstrated its performances for real-time mass sensing. Finally, the proposed TPO mass sensor possesses several key features, including real-time monitoring, fast response time, and most importantly, excellent mass resolution of only 83 fg extracted from the measured TPO’s Allan deviation. [2017-0085]

Extensive performance evaluations of RF MEMS single-pole-multi-throw (SP3T to SP14T) switches up to X-band frequency

This work presents wide range of compact and reliable single-pole-multi-throw (SPMT) radio frequency (RF) microelectromechanical system (MEMS) switches where the M (output) varies from 3 to 14 throws. The single dc-contact switch dimensions are 0.144 mm × 0.29 mm which are fabricated on 635 µm alumina substrate using a surface micromachining process. SPMT switching networks demonstrate a measured return loss of more than 14 dB, a worst case insertion loss of ~1.76 dB and isolation of ~14.5 dB up to 12 GHz. The maximum area of the fabricated SPMT switch is ~1.2 mm2. The SPMT switches are capable of handling 1 W of RF power up to >1 billion cycles at 25 °C, and sustained even up to >80 million cycles with 0.5 W at 85 °C. To the best of our knowledge, this is the first reported wide range of MEMS SPMT switches and their respective performance evaluations in the literature that has undergone extensive measurement stages.

77 GHz polarization reconfigurable micromachined antenna for automotive radar applications

A 77 GHz polarization reconfigurable patch antenna employing radio frequency micro-electromechanical system (RF MEMS) based single-pole-single-throw (SPST) switch is designed and fabricated on 635 µm alumina substrate using surface micromachining process. The total area of the device is 0.794 mm2. Polarization diversity among linear polarization (LP), right hand circular polarization (RHCP) and left hand circular polarization (LHCP) can be produced by controlling the bias voltage of individual SPST switch. Experimental results of SPST switch and proposed antenna is presented.