Excellent Radio Frequency Performance Research Articles

Analysis of the Failure and Performance Variation Mechanism of MEMS Suspended Inductors with Auxiliary Pillars under High-g Shock.

Microelectromechanical systems (MEMS) suspended inductors have excellent radio frequency (RF) performance and they are compatible with integrated circuit (IC). They will be shocked during manufacturing, transportation, and operation; in some applications, the shock amplitude can be as high as tens of thousands of gravitational acceleration (g, 9.8 m/s2). High-g shock will lead to the inductor deformation which affects its performance or even failure of the inductor structure. However, few studies have been carried out on the inductors under high-g shock. In this study, a kind of MEMS suspended inductor with excellent RF and mechanical performance is designed and fabricated. The failure and performance variation mechanism of the inductor under high-g shock is analyzed by measuring and comparing the performance measurement results and the π model parameters extraction results of the inductors before and after air cannon shock test. The results show that the increase of energy loss caused by substrate parasitic effect and the properties variation of the coil material affected by high-g shock are the main reasons for the decrease of RF performance parameters, and the critical stress exceeding the interlayer adhesion is the main reason for the failure of the inductor.

Small signal model and RF performance analysis of InAs/GaSb hetero-junction tunneling field effect transistor

This work presents a comprehensive study of small-signal parameters based on radio frequency (RF) data of a heterojunction tunnel field effect transistor (HJ-TFET). The TFET device shows excellent small-signal analog and RF performance. Numerical device simulations of the optimized HJ-TFET shows ION/IOFF ratio of ~6 orders of magnitude. It is found that gate voltage dependency of HJ-TFET on the intrinsic parameters obtained from the non-quasi static (NQS) model differ from the conventional MOSFET due to band to band tunneling mechanism and inversion layer formation in the device. Based on this mechanism, the high frequency analog and RF performance of HJ-TFET were investigated using TCAD and modeled using NQS model, which was verified upto 100 GHz. The modeling results showed excellent agreement with the simulated small-signal parameters at multiple drain voltages (Vd). f

Miniaturized DC–60 GHz RF PCM GeTe-Based Monolithically Integrated Redundancy Switch Matrix Using T-Type Switching Unit Cells

This article presents an approach to monolithically implement radio-frequency (RF) phase change material (PCM) germanium telluride (GeTe) T-type switch as a switching unit cell for millimeter-wave (mmWave) redundancy switch matrix applications. The miniature T-type switch demonstrates three states of operation, including one crossover state and two turn states. A seven-layer microfabrication process, including an additional conductive layer to reduce the $RC$ time constant due to the bias network routing, is developed and optimized to fabricate the multiport RF devices. A $4 \times 6$ PCM-based redundancy switch matrix is developed by monolithically integrating four T-type switches in the cascade configuration. Thermal crosstalk in PCM switches is experimentally investigated using submicrometer spatial resolution transient thermal imaging. The presented T-type switch has the device periphery of 0.55 mm $\times \,\,0.55$ mm, while the overall integrated PCM redundancy switch matrix is fabricated with a device footprint of 0.88 mm $\times \,\,1.1$ mm. The measured results of the T-type switches demonstrate an excellent RF performance with lower than 1.6 dB insertion loss, better than 20 dB return loss, and higher than 20 dB isolation in all states from dc–67 GHz. The redundancy switch matrix exhibits an insertion loss less than 3 dB, return loss better than 14 dB, and isolation higher than 20 dB from dc–60 GHz. To the best of our knowledge, this is the first implementation of a PCM-based redundancy switch matrix.

Analysis of the Performance Variation Mechanism of MEMS Suspended Inductors under Mechanical Shock.

Micro-electromechanical system (MEMS) suspended inductors have been widely studied in recent decades because of their excellent radio frequency performance. However, the deformation of the inductor coil and the performance variation usually occur to the MEMS suspended inductors when the inductors are under mechanical shock. Few studies have been carried out on the performance variation of MEMS suspended inductors under shock. In this study, the mechanism of the performance variation of MEMS suspended inductors under mechanical shock is analyzed by combining theoretical analysis and experiments. A theoretical analysis based on the lumped-element equivalent model is presented and shock tests are carried out. The shock tests show that the main reason of the MEMS suspended inductor performance variation after mechanical shock is the variation of the substrate parasitic effect, which is caused by the variation of the suspension height of the inductor after shock. The test results agree with the theoretical analysis.

A Compact 16-Way High-Power Combiner Implemented Via 3-D Metal Printing Technique for Advanced Radio-Frequency Electronics System Applications

In this paper, a size-compact and monolithically integrated millimeter-wave 16-way high-power combiner for advanced radio-frequency (RF) electronics applications is developed featuring a wide operational bandwidth and high isolations between the combiner's adjacent ports. The proposed combiner is operating at the X band and is composed of fifteen 3-dB directional coupler units that are properly configured to achieve the overall structural compactness. The combiner is fast-prototyped as a single part by employing a metallic three-dimensional (3-D) printing technique, which successfully overcomes the difficulty in its monolithic implementation by using conventional subtractive manufacturing techniques. The experimental results demonstrate that the 16-way power combiner achieves an approximately 21% operational bandwidth (8.5–10.5 GHz) at the X band with port isolations of more than 20 dB, an amplitude imbalance of about ±1 dB, a phase deviation of around ±1°, and good return and insertion losses. The excellent RF performance of the combiner makes it a good candidate for applications in multiport high-power electronics systems where highly efficient power transmission and conversion among different ports are required.

Micro-fabricated wideband band-stop filter using GaAs-based integrated passive device technology

This paper presents a new concept of implementing a micro-fabricated wideband band-stop filter on a gallium arsenide (GaAs) substrate using integrated passive device technology. The incorporation of an air-bridge structure was explored to enhance design flexibility and achieve excellent radio-frequency performance of the filter. A wideband band-stop filter was realized on a GaAs substrate, generating an insertion loss of − 0.37 dB and a return loss of − 38 dB with excellent attenuation of − 28.78 and − 22.27 dB, in the lower and the upper passband, respectively. The filter resonates at 10.72 GHz, occupying a die area of 2000 μm × 1540 μm. The selectivity of the filter is reflected by its tremendous suppression of out-of-band signals with the existence of attenuation poles in the vicinity of the resonance frequency. Experimental verification of the filter response demonstrates its potential use as an on-chip device operating in the X-band frequency spectrum.

Multi‐contact radiofrequency microelectromechanical systems switch with power divider/combiner structure for high power applications

Design, fabrication, and measurement of a metal-contact radiofrequency (RF) microelectromechanical systems switch with a power divider/combiner structure for high power applications are presented in this work. The multi-contact switch with parallel cantilever beams is implemented in a Y-junction power divider/combiner, which suppresses the uneven current distribution through each contact and results in higher power handling capability at high frequency. The measurement results indicate the excellent RF performance of the switch fabricated on the Borofloat glass substrate with insertion loss and isolation of 0.22 dB and 29 dB@10 GHz, respectively. A lumped-element model is developed and it fits well with the measured S-parameters with the contact resistance of 0.6 Ω and up-state capacitance of 1 fF for each contact. The switch can handle power up to 2 W@10 GHz under prolonged hold-down conditions for 2 h. The reliability measurement shows that the packaged switch can operate for over 1 million cycles at 200 mA under cold-switching conditions.

Failure mode analysis of MEMS suspended inductors under mechanical shock

Micro-electromechanical system (MEMS) suspended inductors have been widely studied in recent decades because of their excellent radio frequency performance. However, few studies have been performed on the failure analysis of MEMS suspended inductors under mechanical shock. In this study, the failure of MEMS suspended inductors with a planar spiral coil is investigated through analytical and experimental methods. We present a stress and deformation analysis to study the failure mode of the suspended inductors under shock. To verify the theoretical analysis, MEMS inductors are designed and fabricated, and shock tests are carried out. The shock tests show that the failure mode of the MEMS suspended inductors is a fracture that occurs at the ends of the inductor coil, and the test results agree with the theoretical analysis.

Circuit Modelling and Eigenfrequency Analysis of a Poly-Si Based RF MEMS Switch Designed and Modelled for IEEE 802.11ad Protocol

This paper presents the equivalent circuit modelling and eigenfrequency analysis of a wideband robust capacitive radio frequency (RF) microelectromechanical system (MEMS) switch that was designed using Poly-Si and Au layer membrane for highly reliable switching operation. The circuit characterization includes the extraction of resistance, inductance, on and off state capacitance, and Q-factor. The first six eigenfrequencies are analyzed using a finite element modeler, and the equivalent modes are demonstrated. The switch is optimized for millimeter wave frequencies, which indicate excellent RF performance with isolation of more than 55 dB and a low insertion loss of 0.1 dB in the V-band. The designed switch actuates at 13.2 V. The R, L, C and Q-factor are simulated using Y-matrix data over a frequency sweep of 20-100 GHz. The proposed switch has various applications in satellite communication networks and can also be used for devices that will incorporate the upcoming IEEE Wi-Fi 802.11ad protocol.

T-Gate Aligned Nanotube Radio Frequency Transistors and Circuits with Superior Performance

In this paper, we applied self-aligned T-gate design to aligned carbon nanotube array transistors and achieved an extrinsic current-gain cutoff frequency (ft) of 25 GHz, which is the best on-chip performance for nanotube radio frequency (RF) transistors reported to date. Meanwhile, an intrinsic current-gain cutoff frequency up to 102 GHz is obtained, comparable to the best value reported for nanotube RF transistors. Armed with the excellent extrinsic RF performance, we performed both single-tone and two-tone measurements for aligned nanotube transistors at a frequency up to 8 GHz. Furthermore, we utilized T-gate aligned nanotube transistors to construct mixing and frequency doubling analog circuits operated in gigahertz frequency regime. Our results confirm the great potential of nanotube-based circuit applications and indicate that nanotube transistors are promising building blocks in high-frequency electronics.

Impedance-Isolation Technique for ESD Protection Design in RF Integrated Circuits

SUMMARY An impedance-isolation technique is proposed for on-chip ESD protection design for radio-frequency (RF) integrated circuits (ICs), which has been successfully verified in a 0.25-μm CMOS process with thick top-layer metal. With the resonance of LC-tank at the operating frequency of the RF circuit, the impedance (especially, the parasitic capacitance) of the ESD protection devices can be isolated from the RF input node of low-noise amplifier (LNA). Therefore, the LNA can be codesigned with the proposed impedance-isolation technique to simultaneously achieve excellent RF performance and high ESD robustness. The power gain (S21-parameter) and noise figure of the ESD protection circuits with the proposed impedance-isolation technique have been experimentally measured and compared to those with the conventional double-diodes ESD protection scheme. The proposed impedance-isolation technique had been demonstrated to be suitable for on-chip ESD protection design for RF ICs.

Near-Ballistic Uni-Traveling-Carrier Photodiode- Based V-Band Optoelectronic Mixers With Internal Up-Conversion-Gain, Wide Modulation Bandwidth, and Very High Operation Current Performance

We construct a high-performance optoelectronic mixer by integrating a near-ballistic uni-traveling-carrier photodiode with a V-band (50-75 GHz) coplanar-waveguide-based bandpass filter. The demonstrated device shows an improvement in the V-band output radio-frequency (RF) power and conversion loss of around 3 and 10 dB, respectively, over that of the control device, which does not have such an integrated filter. The strong nonlinearity of the ballistic-transport of the electrons in the active device, and the excellent RF performance of the integrated filter help us to achieve an internal-conversion gain of around 1 dB, from the low to very high optical injected local-oscillator power (20.6 dBm), which corresponds to an approximately 17-mA high-output photocurrent, and very wide up-conversion bandwidth (>15 GHz) at the V-band.

Single-Pole Eight-Throw RF MEMS Rotary Switch

The design, fabrication, and measured performance of a novel single-pole eight-throw radio-frequency (RF) microelectromechanical systems (MEMS) rotary switch are described. The concept of this rotary switch is based on the adaptation of the axial gap wobble motor. A prototype switch has been made using separately fabricated stator, rotor, and cap components that are then assembled. A rigorous procedure was setup to investigate the direct current (dc) contact resistance over a total of four million rotor contact closures, with half a million closures made on each of the eight stator contacts. It was found that there was no obvious systematic trend in contact resistance over time. An average contact resistance of 2.5 Omega was recorded; however, values as low as 1.0 Omega were also found. The assembled rotary switch demonstrated an excellent RF performance. With the inclusion of feed lines, the insertion loss was 2.65 dB at 20 GHz, after renormalizing the measurement reference impedance. When the loss of the feed lines is subtracted, the worst-case on-state intrinsic insertion loss of the rotary switch is only 2.16 dB at 20 GHz. A worst-case off-state isolation of 31 dB was also measured over the 20-GHz bandwidth. The effective performance figure-of-merit for this switch in an arbitrary position was calculated to be 10.7 THz. To the authors' knowledge, this is the first example of a true single-pole multiple-throw RF MEMS rotary switch

GSM transceiver front-end circuits in 0.25-μm CMOS

So far, CMOS has been shown to be capable of operating at radio-frequency (RF) frequencies, although the inadequacies of the device-level performance often have to be circumvented by innovations at the architectural level that tend to shift the burden to the circuit building blocks at lower frequencies, The RF front-end circuits presented in this paper show that excellent RF performance is feasible with 0.25-/spl mu/m CMOS, even in terms of the requirements of the tried-and-true superheterodyne architecture. Design for low-noise and low-current consumption targeted for GSM handsets has been given particular attention in this paper. Low-noise amplifiers with sub-2-dB noise figures (NFs) and a double balanced mixer with 12.6 dB single-sideband NF, as well as sub-25-mA current consumption for the RF front end (complete receiver), are among the main achievements.

Application of SiGe heterojunction bipolar transistors in 5.8 and 10 GHz low-noise amplifiers

The development of wireless services in the 5 – 10 GHz region demands low-cost radio frequency (RF) monolithic microwave integrated circuits, with SiGe heterojunction bipolar transistors as a likely technology, combining the low cost of a mature silicon technology with excellent RF performance. These transistors are particularly attractive candidates for low-noise applications. The authors demonstrate 5.8 and 10 GHz low-noise amplifiers exhibiting a minimum noise figure of 1.6 and 3.3 dB, respectively, and a power gain above 12 dB.