Single Pole Multi-throw Research Articles

A low insertion loss RF switch using a 130 nm SOI process

To realize a better radio frequency (RF) communication system, the RF switch, as an important module, is used to cooperate with other devices to form an RF front end for optimizing communication performances. This paper designs a single-pole multi-throw (SPMT) RF switch, which exhibits a low insertion loss of 0.57 dB at 1.9 GHz under the voltage of 2.2 to 4.7 V. The RF switch is fabricated using a 130 nm silicon-on-insulator (SOI) complementary metal-oxide-semiconductor (CMOS) process. It can be used in multi-frequency and multi-mode applications such as 4G/5G. The proposed RF switch has competitive performance and can be combined with other modules to achieve better wireless communication and promote the development of ultra-wideband and multi-mode wireless communication systems.

Phase Modulation Technique for Harmonic Beamforming in Time-Modulated Arrays

In this article, a novel high-efficiency harmonic beamforming technique based on time-modulated arrays (TMAs) with multistate time modulators is proposed. The typical single-sideband TMAs suppress the image harmonic components in the radio frequency (RF) channel, which means low power conversion efficiency, large power consumption, and a major heat dissipation problem. To circumvent these constraints, we present a novel phase modulation (PM) waveform with a linear phase that can be easily constructed using multiple fixed delay lines and a pair of single-pole-multi-throw (SPMT) RF switches. This fundamental PM waveform enables the creation of uniform radiation patterns. Furthermore, two complementary methodologies are proposed for synthesizing more advanced radiation patterns that need nonuniform array weights. One method is to change the linear phase slope of PM waveforms that exhibit sideband radiation but have 100% feeding network efficiency. The other option is to investigate hybrid amplitude and PM (HAPM) waveforms, which suffer from inefficiencies in the feeding network but do not exhibit sideband radiation. Besides, the comprehensive efficiency evaluation formulas have been effectively derived. Simulations have been done to verify its effectiveness.

1.866–2.782-GHz Reconfigurable Filtering Single-Pole-Multithrow Switches Based on Evanescent-Mode Cavity Resonators

In this article, novel reconfigurable filtering single-pole-multithrow (SPMT) switches based on the evanescent-mode cavity (EVA) are proposed. The design incorporates varactors between two EVA resonators. By controlling the varactor capacitance value, the coupling coefficient between resonators can be set to be zero or desired value which allows the corresponding signal path to be in OFF-state with high isolation or in ON-state with bandpass filter response. Based on this technique, filtering SPMT switches can be achieved with reconfigurable frequencies. Moreover, each filtering-switch path shares two common resonators with others, which significantly reduce the filter size and make the proposed SPMT very compact. A filtering single-pole-double-throw (SPDT) switch and a filtering single-pole-5-throw (SP5T) switch were designed, fabricated, and measured to demonstrate the proposed technique. These filtering switches can be continuously tuned from 1.953-2.782 and 1.866-2.257 GHz, respectively, with isolation better than 47.2 and 36.1 dB, respectively. Good agreement is obtained between simulated and measured results.

Physics based non-linear large-signal analysis of multiple-graphene layer exotic pin (p++–n−–n–n++) devices and ultra-fast SPST/SPDT/SPMT switches on Si/3C-SiC (100) substrates for application in THz-communication

Multiple-Graphene-Layer (MGL) on Si/3C-SiC (100) substrate is proposed for designing of a vertically doped p++–n−–n–n++ device/switch array for Terahertz communication systems. In addition to the superior mechanical properties in Graphene, conducive–electrical and electronic properties, especially, high carrier mobility in MGL has made this a promising material for different novel applications in THz domain. A quantum-modified classical drift–diffusion (QMCLDD) mathematical model, incorporating quantum size effects, arising due to Multiple-Graphene-Layer, is developed by the authors for analysing the THz-characteristics of exotic-pin p++–n−–n–n++ devices and switches. The validity of the model is further established by comparing the simulation results with those of the experimental observations under similar electrical/thermal/structural operating conditions. The comprehensive study reveals that the switching behaviour of the device improves considerably due to the incorporation of MGL structure in the central i-region of the device. The device has shown considerably faster reverse recovery time (~ 0.5 ns), low forward RF series resistances (0.29Ω) and low power dissipation (0.45 dB). Central i-region width, doping concentration and mesa diameter of the device are optimized by studying the punch-through effects on the electric field profiles under large signal operation. It is observed that compared to the High-Punch-Through Device (HPTD) and Non-Punch-Through Device (NPTD), Low-Punch-Through Device (LPTD) is showing better high-frequency performances under similar operating conditions. A tradeoff between device width and doping concentration is further established for ultra-fast switching operation in the THz-regime. A comparative analysis of Insertion loss (IL) and Isolation (ISO) in Single-Pole-Single-Throw (SPST), Single-Pole-Double-Throw (SPDT) and Single-Pole-Multi-Throw (SPMT) THz-switches (with series–shunt and Shunt type arrays) is reported in the paper. The study clearly reveals the suitability of LPTD variant for the development of SPST switches in terms of lowest IL (0.015 dB) and SPMT shunt switches in terms of highest ISO (88.0 dB) at around 4.0 THz. Moreover, the authors have made quasi 2D-thermal analysis of the Device-Under-Test (DUT). The results will be extremely useful for developing ultrafast solid-state switches. To the best of authors’ knowledge this is the first ever report on vertically grown MGL-exotic pin (p++–n−–n–n++) device on Si/3C-SiC (100) substrate, as a THz ultrafast switch.

III–V super-lattice SPST/SPMT pin switches for THz communication: theoretical reliability and experimental feasibility studies

A physics-based Quantum-Modified CLassical Drift–Diffusion (QMCLDD) non-linear mathematical model has been developed for design and characterisation of GaN/AlGaN asymmetrical superlattice pin based single-pole single-throw (SPST) and single-pole multi-throw (SPMT) switches for sub-MM wave communication systems. The simulator has incorporated several important physical phenomena that arise in superlattice structure, including quantum confinement effects, generation-recombination and tunnelling generation of carriers as well as scattering limited carrier mobility and velocity in GaN/AlGaN structure. In order to reduce the dislocation density and in turn the series resistance in GaN/AlGaN heterostructure, thin AlN nucleation layer and a buffer layer are considered in the simulation. It is observed that the RF series resistance of the pin device, operating around 0.2 THz frequency regime, reduces in case of proposed superlattice structure. The advantages of super-lattice pin diode over the conventional Si devices are the faster reverse recovery time (~ 9 vs 35 ns) and lowering of forward RF series resistances (0.39 vs 1.20 Ω). This study also reveals that SPST and SPMT switches made up with super-lattice devices are characterized by low insertion loss (~ 0.13 and 0.15 dB, respectively) and high isolation (~ 65.4 and 82.5 dB, respectively). A good agreement between theory and experiment establishes the superiority of the present model over the others. A comparative analysis of Si and GaN/AlGaN super-lattice pin SPST and SPMT switches establishes the potential of the later for its application in high-frequency THz-communication. In addition to this, a detailed thermal modelling of the device has also been done to make the analysis more realistic. The junction temperature of the designed GaN/AlGaN superlattice pin switch will be as high as 377 K, which is quite moderate compared to its flat profile counterpart. To the best of authors’ knowledge, this is the first ever report on QMCLDD non-linear modelling of pin SPST and SPMT switches (series-shunt combination) at THz-arena.

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.

A Circularly Polarized Switched-Beam Antenna Array

This letter introduces a novel, inexpensive, and low-insertion-loss switch feeding network for beam steering of antenna array. The proposed network uses only a single-pole multithrow (SPMT) microwave p-i-n switch to steer the main beam to different angles with high gains. In theory, arbitrary angles and an arbitrary number of steering beams can be realized with this structure. This type of switch feeding network is used to successfully design a 2×3 circular polarization microstrip antenna array, and the experimental results are presented and discussed. Good agreements between simulation and testing are achieved.

RF MEMS Switches and Integrated Switching Circuits

Radio frequency (RF) microelectromechanical systems (MEMS) have been pursued for more than a decade as a solution of high-performance on-chip fixed, tunable and reconfigurable circuits. This paper reviews our research work on RF MEMS switches and switching circuits in the past five years. The research work first concentrates on the development of lateral DC-contact switches and capacitive shunt switches. Low insertion loss, high isolation and wide frequency band have been achieved for the two types of switches; then the switches have been integrated with transmission lines to achieve different switching circuits, such as single-pole-multi-throw (SPMT) switching circuits, tunable band-pass filter, tunable band-stop filter and reconfigurable filter circuits. Substrate transfer process and surface planarization process are used to fabricate the above mentioned devices and circuits. The advantages of these two fabrication processes provide great flexibility in developing different types of RF MEMS switches and circuits. The ultimate target is to produce more powerful and sophisticated wireless appliances operating in handsets, base stations, and satellites with low power consumption and cost.

RF MEMS technology

AbstractRecently, to meet the demands of multimode/multiband functions for the next generation communication systems, RF MEMS technology is being developed for the reconfigurable transceiver system. In this article, RF MEMS devices such as switches, high‐Q inductors, and high‐Q resonators are reviewed for their operating principles and device structures, as well as the reliability and commercial issues. Single pole single throw (SPST)‐type MEMS switches show characteristics superior to solid‐state switches in the aspects of insertion loss, isolation, and linearity. Single pole multithrow (SPMT) switches will enable ultra small‐sized cellular phones, but insertion loss and coupling between channels should be improved. For a high‐Q inductor, out‐of‐plane inductors show improved results, and an inductor with a Q‐factor of 75 at 1GHz has been fabricated by using the internal stress of a MoCr film. The MEMS inductor improves the performance of a voltage controlled oscillator (VCO), but proper hermetic packaging and standard libraries are also necessary for mass production. The MEMS resonator can operate up to 1.4 GHz and can be used as an oscillator for the timing device as well as component of the filter circuit. The SiTime Company recently has started delivery of a product with performance similar to the quartz oscillator, in which they solved the reliability issues by modifying the annealing and vacuum packaging. Copyright © 2007 Institute of Electrical Engineers of Japan© 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Design Considerations for Traveling-Wave Single-Pole Multithrow MMIC Switch Using Fully Distributed FET

The circuit design considerations for the traveling-wave switch (TWSW) single-pole double-throw (SPDT) monolithic microwave integrated circuit (MMIC) utilizing a fully distributed FET (FD-FET) are presented here for the first time. The normalized length of the impedance transformer for a single-pole multithrow TWSW using the FD-FET is found to be less than a quarter-wavelength at the operating frequency. Unlike the TWSW using lumped FETs, the TWSW with the FD-FET offers the advantage of no design limits regarding such frequency characteristics as bandwidth and group delay. The newly developed SPDT TWSW MMIC using the 400-mum-gate finger FD-FET delivers broadband characteristics over more than an octave frequency range with highly reliable MMIC technology. The newly developed SPDT MMIC switch provides low insertion loss of less than 2.1 dB and high isolation of over 25.5 dB from 38 to 80 GHz, coupled with the benefit of very small size