RF Switch Research Articles

Accurate Phase Calibration of Multistatic Imaging System for Medical and Industrial Applications

Multistatic imaging systems are commonly used in radar systems and microwave imaging. In these systems, many antennas are arranged three-dimensionally and connected to RF switches. The length of each transmitter (Tx) and receiver (Rx) channel differs slightly, causing artifacts in high-resolution image reconstruction. This study presents a novel method for the phase calibration of multistatic systems. This method does not require system reconstruction and can automatically perform phase calibration in a short time. This method is expected to facilitate an accurate phase measurement in multistatic systems. The approach involves phase calibration by analyzing the reflection coefficients of antenna elements in the time domain. Imaging experiments were performed on a multistatic imaging system using this calibration method, and the position and shape of a metal rod with a diameter one-fourth of a wavelength were reconstructed by simple back-projection with an accuracy beyond the diffraction limit.

High Power Capacity Mechanical RF Switch Using Liquid Metals as Wetted Contacts

High Power Capacity Mechanical RF Switch Using Liquid Metals as Wetted Contacts

A Nonlinear Model of RF Switch Device Based on Common Gate GaAs FETs

ABSTRACTThis paper presents a novel method for nonlinear modeling GaAs field‐effect transistors (FETs) in a common gate (CG) configuration, which is crucial for the effective design and thorough assessment of RF switch circuits. By focusing solely on a CG‐based GaAs FET for RF switch device characterization and modeling, the modeling process is streamlined compared to traditional methods that involve both CG and common source (CS) devices. The direct measurement of both DC and RF characteristics using the CG device enhances the accuracy of model parameter extraction. This approach ensures consistency in model and simulation applications as the CG topology aligns with devices commonly found in RF switch circuits. Moreover, to enhance predictive accuracy regarding the dispersion effect, an improved equation of drain‐source current has been incorporated. The empirical validation of the model reveals good agreements in terms of insertion loss, isolation, and output power performance for the CG GaAs FET device, including a wide band single‐pole double‐throw (SPDT) switch Monolithic Microwave Integrated Circuit (MMIC).

Indigenous Development of MIC-Based C-Band Dual Chain Down Converter Unit for GEOSAT- Spacecraft Checkout System

As part of miniaturization, the development work for the C-band dual-chain down converter, which is extensively used in TM (Telemetry) data acquisition system in GEOSAT spacecraft checkout system has been taken up in MIC (Microwave Integrated Circuit) approach using microstrip line structure. A prototype unit is realized using standard surface mount devices (SMD) and few indigenously developed MIC components namely, the directional couplers, the power dividers etc. The MIC-based down converter module, which forms the heart of the unit is housed in an Aluminium milled box having the dimension of 150 x 150 x 25 mm3. Except internal Local Oscillator (LO), RF Switches and Power supply, all other circuitry are mounted withinthis milled box which is housed in 1U chassis. It meets all the requirements of a conventional down converter. The paper describes the salient features of the unit, its detailed design approach and realization plan and finally the test and evaluation results of the prototype unit developed indigenously.

Development and Characterization of an Advanced Voltage-Controllable Capacitor Based on AlInGaN/GaN-Si (111) Epitaxy

The AlInGaN/GaN heterojunction epitaxy material with high cutoff frequency and saturated power density has become a very popular candidate for millimeter wave applications in next-generation mobile communication. In this study, an advanced voltage-controllable capacitor based on the AlInGaN/GaN-Si (111) epitaxy was proposed by employing a bi-directional series MIS capacitor structure. The capacitor was fabricated by using a pad area of 40 μm × 40 μm, with a 1 μm distance between the positive and negative electrodes. The test results show that the capacitance is turned on with a saturation capacitance density and a maximum leakage current density of 0.30 fF/μm2 of 0.37 pA/μm2, respectively, for the control voltage from −6.5 V to 6 V. In particular, in the proposed design method, the saturation capacitance required for the practical application can be obtained by simply adjusting the capacitance area. The capacitor showcases characteristics of rapid turn-on and turn-off responses coupled with low loss, underscoring its promising prospects for deployment in RF switching applications.

An Adaptive RF Front-End Architecture for Multi-Band SDR in Avionics.

This study introduces a reconfigurable and agile RF front-end (RFFE) architecture that significantly enhances the performance of software-defined radios (SDRs) by seamlessly adjusting to varying signal requirements, frequencies, and protocols. This flexibility greatly enhances spectrum utilization, signal integrity, and overall system efficiency-critical factors in aviation, where reliable communication, navigation, and surveillance systems are vital for safety. A versatile RF front-end is thus indispensable, enhancing connectivity and safety standards. We explore the integration of this flexible RF front-end in SDRs, focusing on the detailed design of essential components, such as receivers, transmitters, RF switches, combiners, and splitters, and their corresponding RF pathways. Comprehensive performance evaluations confirm the architecture's reliability and functionality, including an extensive analysis of receiver gain, linearity, and two-tone test results. These assessments validate the architecture's suitability for aviation radios and address considerations of size, weight, and power-cost (SWaP-C), demonstrating significant gains in operational efficiency and cost-effectiveness. The introduction of the new RF front-end on a single SDR board not only substantially reduces size and weight but also adds up to 18 dB gain to the received signal. It also allows for a high level of design flexibility, enabling seamless software transitions between different radios and the capacity to manage three times more radios with the same hardware, thereby significantly boosting the system's ability to handle multiple radio channels efficiently.

Embedded system controlled switching system for reconfigurable antennas

AbstractA multiband and reconfigurable antenna is the one of the main aspects in the communication system which has an extremely important role. An embedded based solution for the fast operation of a reconfigurable antenna to work in a specific operating frequency band is the solution of future technologies. Embedded based solution increases the speed by avoiding the dependence on manual control of the RF switching elements. In this paper, the proposed embedded system‐controlled switching mechanism operate the reconfigurable antenna in any one of the operating bands by a single command to be send from a remote location. The embedded system receives the command and configure a set of PIN diodes as per the modes. The proposed solution consists an Arduino UNO board as motherboard, SIM900A as GSM module to receive the command from user, biasing circuit to control the operation of PIN diode, PIN diode to reconfigure the patch pattern and a user mobile for sending AT command.The proposed model is successful and tested on proteus software 8.0. The model is also deployed on the newly designed multiple‐input‐multiple‐output antenna where the result shows the successful operation to achieve multiband frequency operation.

Downconversion master slave optical coherence tomography for simultaneous en-face imaging at two depths.

We report the production of two en-face optical coherence tomography (OCT) images from two different depths in real time, using three interferometers in a configuration of double downconversion master slave OCT. Two active mixers are used to produce the analog product of two photodetection signals. A low-cost digitizer with a sampling rate just at the level of twice the inverse of the tuning interval is used, with a much lower sampling rate than that required by the conventional A-scan-based OCT imaging at the same tuning rate. Not employing a fast digitizer for the photodetected signal, as conventional OCT imaging does, the selection of temporal windows from the photodetected signals is achieved by low-cost RF switches. Optimum conditions for the active mixers and switches employed are evaluated to optimize the downconversion operation.

X‐band high isolation single pole double throw switch based on resonant concept

AbstractUtilizing the 0.25 μm GaN HEMT process, a high‐isolation single pole double throw (SPDT) RF switch has been meticulously designed for the X‐band. The circuit topology employs a series‐shunt configuration to prevent signal leakage, thereby enhancing chip isolation. By incorporating series transistors and shunt inductors, LC resonance is achieved, significantly boosting isolation performance. To optimize port matching and ensure both heightened isolation and minimized insertion loss, inductors are strategically integrated into each port. The inclusion of these lumped inductors contributes significantly to reducing the chip's footprint. Die measurement results demonstrate that across the 8–12 GHz frequency spectrum, insertion loss remains below 1.1 dB, with isolation exceeding 36 dB. Remarkably, at 10.5 GHz, isolation peaks at an impressive 52 dB. Moreover, return loss surpasses 12 dB, and the 0.1 dB compression point input power stands at 43.5 dBm, all achieved within a compact chip area of only 1 mm2.

Comprehensive Review of RF MEMS Switches in Satellite Communications.

The miniaturization and low power consumption characteristics of RF MEMS (Radio Frequency Microelectromechanical System) switches provide new possibilities for the development of microsatellites and nanosatellites, which will play an increasingly important role in future space missions. This paper provides a comprehensive review of RF MEMS switches in satellite communication, detailing their working mechanisms, performance optimization strategies, and applications in reconfigurable antennas. It explores various driving mechanisms (electrostatic, piezoelectric, electromagnetic, thermoelectric) and contact mechanisms (capacitive, ohmic), highlighting their advantages, challenges, and advancements. The paper emphasizes strategies to enhance switch reliability and RF performance, including minimizing the impact of shocks, reducing driving voltage, improving contacts, and appropriate packaging. Finally, it discusses the enormous potential of RF MEMS switches in future satellite communications, addressing their technical advantages, challenges, and the necessity for further research to optimize design and manufacturing for broader applications and increased efficiency in space missions. The research findings of this review can serve as a reference for further design and improvement of RF MEMS switches, which are expected to play a more important role in future aerospace communication systems.

TCAD Simulation of Novel Recess Gate Common Drain Dual Channel AlGaN/GaN HEMT for Small Signal Performance

In this paper, DC and RF characteristics of Recess Gate Common Drain Dual Channel (CDDC) AlGaN/GaN HEMT have been investigated. The performance of the device in terms of the various figures of merits including gate-source capacitance, drain current, transconductance, and channel conductance has been studied for different recess depths. The threshold voltage is found to decrease by shifting right with increasing recess depth, even though with deeper recess, transconductance increases. It has also been observed that the device operates in enhancement mode with a minimum gate recess depth of 15 nm or more. With increasing recess depth, the drain current starts decreasing due to an increase in channel resistance. Use of recess technology with Al graded barrier layer enhances the performance in terms of gm, ft, and fmax which are 0.003 S, 23, and 46 GHz, respectively, but utilizing gate recess technology alone in CDDC HEMT further enhances device performance and the maximum gm, ft, and fmax are 0.0442 S, 28.43, and 59.21 GHz. The CDDC HEMT retain its advantage for specific applications including PA, LNA, and RF switch with optimized gate recess and graded barrier layer parameters.

Arbitrary Shaped High-Voltage RF Switch

Arbitrary Shaped High-Voltage RF Switch

WLCSP Fully Protected Fan-In Reliability

A strong supply chain requires higher performance and lower cost processes. DCA conventionally referred to as WLCSP has been used for low density devices, however for higher density devices reliability concerns have emerged. Six-side protected, aka “6S or fully protected”, CSP is a rapidly growing market. Fully protected CSP was first implemented with processes such as M-series utilizing FO. These processes require costly and complex die reconstitution, expensive tapes, molding, and other operations. These steps can be eliminated in a P-WLCSP process to provide the cost-effective high reliability 6S format needed for high-performance higher pin count and/or thin silicon chips. American Semiconductor’s Semiconductor-on-Polymer (SoP) 300mm SoP-TM, a P-WLCSP process, is an advanced packaging process optimized for protected CSP, fan-in, and chiplets. Protected FI process innovations can improve performance in power devices, RF switches, photonic IC (PIC), die stacking and thin board applications. The P-WLCSP process incorporates the best of DCA (simplicity) and FO (protection) while incorporating advanced manufacturing processes to lower cost and improve performance. This paper builds on the SoP-TM process release announced at the 2023 Device Packaging Conference earlier this year with the addition of reliability characterization beyond first silicon data for electrical test chips. Reliability data such as accelerated stress tests, die strength, operating lifetime and thermal testing are key areas of investigation for the new P-WLCSP technology that will be presented. The presentation will also include and update for ultra-thin device reliability test methods under consideration for new NIST standards.

RF Switch Integrated With CSRR Array for Subsurface Imaging of Composite Structures

RF Switch Integrated With CSRR Array for Subsurface Imaging of Composite Structures

A Large-Signal SPICE Model for a Dual-Gate GaN RF Switch With OFF-State Harmonic Control

A Large-Signal SPICE Model for a Dual-Gate GaN RF Switch With OFF-State Harmonic Control

Design and Optimization of a High-Power Solid-State Plasma RF Switch

Design and Optimization of a High-Power Solid-State Plasma RF Switch

Nanoscale modeling of an efficient Carbon Nanotube-based RF switch using XG-Boost machine learning algorithm

Nanoscale modeling of an efficient Carbon Nanotube-based RF switch using XG-Boost machine learning algorithm

Thin and Ultra-thin Sidewall Protected P-WLCSP

Diversity in packaging for a strong supply chain requires higher performance and lower cost processes for new manufacturers. Six-side protected, aka “6S or fully protected”, CSP is an emerging and rapidly growing market. Fully protected CSP (without substrates or lead-frames) was first implemented with processes such as M-series and eWLB. These processes require costly and complex die reconstitution, expensive tapes, molding, and other operations most common to FO to obtain 6-side die protection. These steps can be eliminated in a wafer level process to provide high-performance low-cost P-WLCSP to enable new CSP manufacturing capability, Fan-In and Chiplets. American Semiconductor’s Semiconductor-on-Polymer (SoP) 300mm SoP-TM, a P-WLCSP process, is an advanced packaging process optimized for protected CSP, fan-in, and chiplets. Protected FI process innovations can improve performance in power devices, RF switches, photonic IC (PIC), die stacking, and thin board applications. This paper builds on the SoP-TM process development provided at the IMAPS Symposium earlier this year with the addition of first silicon data for electrical test chips. SoP-TM test chip features include 10um silicon thickness, metal interconnect and micro-bumps, smooth silicon sidewalls and 6-side polyimide encasement. Reliability data and testing is a key area of investigation for thin-device technology. Ultra-thin device reliability test methods under consideration for new NIST standards will be presented. Mechanical, high temperature and high humidity reliability for SoP-TM test chips, Chip-on-Flex (COF) and Flip Chip using the new test methods will be presented.

High-Voltage Analog Switch Inspired by Stacked MOSFET-Based RF Switches

High-Voltage Analog Switch Inspired by Stacked MOSFET-Based RF Switches

Thermally tunable ethanol impregnated PDMS/CoZTO/SWCNT composite architecture for smart electromagnetic shielding

Shape memory elastomer composites with externally stimulated shielding capability are greatly sought to protect high-end artificial intelligence-based electrical and telecommunication devices in the military, aerospace, robotics, etc., from electromagnetic interference (EMI). However, the fabrication of such composites integrated with externally responsive green EMI shielding capabilities is promising but greatly challenging. Herein, ethanol (thermally active phase) mixed polydimethylsiloxane (PDMS)/single wall carbon nanotube (SWCNT)/cobalt doped zinc tin oxide (CoZTO) hybrid composite with an active guest method was devised. This design strategy explores how the thermally controlled liquid-gas phase transition led microstructural modifications regulate the macroscopic shielding features like absorption enhancement and reflection minimization. The composite adapts the 72.18 % volumetric actuation by liquid-to-vapor phase transition of ethanol at 80 °C, promoting the total EMI shielding value up to 48.77 dB from 18.4 dB at 20 GHz due to microstructure induced electromagnetic modifications. Additionally, a green index of 7.2 confirms the absorption dominance over reflection shielding in the studied composite. Furthermore, ethanol-generated foamed architecture of composite offers pressure-sensitive on-off shielding tunability, which accounts for the potential use in manufacturing advanced RF switches.