Monolithic Microwave Integrated Circuit Applications Research Articles

Design of a Schottky Metal-Brim Structure to Optimize 180–220 GHz Broadband Frequency Doubler MMIC

The present work proposes a 180–225 GHz broadband frequency doubler monolithic microwave integrated circuit (MMIC) based on a novel Schottky barrier diode (SBD) terminal structure denoted as a Schottky metal-brim (SMB). Compared with an MMIC adopting the conventional SBD terminal structure, preliminary measurements show that the maximum output power of the MMIC adopting the SMB structure increases from 0.216 mW at 206 GHz to 0.914 mW at 208 GHz. Analysis of the nonlinear current–voltage and capacitance–voltage characteristics of the two terminal structures based on an extended one-dimensional drift-diffusion model, indicates that the SMB structure provides significantly better conversion efficiency than the conventional SBD structure by eliminating the accumulation of charge and additional current paths near the Schottky electrode edge. It provides a feasible scheme for the optimization of MMIC applications requiring high power and high efficiency.

GaAs metamorphic high electron mobility transistors for future deep space-biomedical-millitary and communication system applications: A review

Following the introduction of metamorphic high electron mobility transistors (MHEMTs) 30 years back, there has been a rapid growth in their use in advanced MMIC (monolithic microwave integrated circuit) and TMIC (Terahertz monolithic integrated circuit) applications in sub-millimetre wave (S-MMW) and terahertz (THz) frequency regime. Undoubtedly, they are capable of making a great impact in applications such as deep space, cryogenic, biomedical instrumentation, military, high speed communication networks etc, in the years to come. This review article not only studies the progress of depletion mode (D-Mode), enhancement mode (E-Mode) type MHEMTs in the last 30 years, extensively but also critically and systematically analyzes the fabrication challenges, reliability issues and their use in cryogenic fields. Yet another highlight is that the work also carefully examines the utility of MHEMTs in deep space, biomedical, scientific, military, communication areas and so forth.

Characteristics of Doped n+ GaAs Thermopile-Based RF MEMS Power Sensors for MMIC Applications

This letter presents characteristics of thermopile-based radio frequency microelectromechanical system (RF MEMS) power sensors with different doped n± GaAs concentrations, in order to improve sensitivity and signal-noise ratio (SNR). These sensors employ the conversion principle of RF power-heat-electricity, where two materials of AuGeNi/Au and n± GaAs are designed to constitute two arms of the thermopile. The effects of four doping concentrations of n± GaAs on the sensitivity and SNR of the power sensors are investigated. The RF MEMS power sensors are fabricated by a GaAs monolithic microwave integrated circuit (MMIC)-compatible process. Experiments show that these power sensors produce return losses of less than -28.3 dB up to 20 GHz. For the doped n± GaAs concentrations of 2.4 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">18</sup> , 8.5 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</sup> , 3.2 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</sup> , and 1.9 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> , measured sensitivities are about 84.10, 101.04, 209.82, and 395.52 μV/mW at 1 GHz and about 45.87, 54.11, 104.15, and 212.53 μV/mW at 20 GHz, respectively, while the resulting SNR are about 4.27 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> , 3.08 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> , 3.91 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> , and 5.70 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> W <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> at 1 GHz and about 2.33 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> , 1.65 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> , 1.94 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> , and 3.06 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> W <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> at 20 GHz, respectively. With the decrease of doping concentration, the sensitivity increases but the SNR decreases first and then increases.

Inline capacitive RF power sensor based on floating MEMS beam for GaAs MMIC applications

A 0.01–20 GHz inline capacitive radio frequency (RF) power sensor with a floating microelectromechanical system (MEMS) beam is proposed. It is based on sensing the capacitance change of the MEMS beam above the coplanar waveguide line due to the electrostatic force. In the design, anchors of the MEMS beam are floating for accurate capacitive detection and flexible for increasing the sensitivity, and an impedance matching technique is utilised to improve the microwave performance. The fabrication of this sensor is compatible with the GaAs monolithic microwave integrated circuits (MMICs) process. The measured reflection loss of the capacitive sensor is <−18 dB, whereas the insertion loss is better than −0.38 dB up to 20 GHz. Experiments show that approximate linear relationships between the measured capacitance change and the input RF power are obtained, and the resulting average sensitivities are 120.8, 76.7, 87.6 and 61.0 aF/mW at 5, 10, 15 and 20 GHz, respectively.

Characterization of MgZnO Thin Film for 1 GHz MMIC Applications

MgZnO thin films are proposed as a new dielectric material for 1 GHz monolithic microwave integrated circuit (MMIC) applications. The high permittivity of this material enables size reduction; furthermore this can be fabricated using a low cost processing method. In this work, MgZnO/Pt/Si thin films were synthesized using a sol-gel spin coating method. The samples were annealed at various temperatures with the effects on physical and electrical properties investigated at direct current (DC) and high frequencies. The physical properties of MgZnO thin film were analyzed using X-Ray diffraction, with the improvements shown in crystalline structure and grain size with increasing temperature up to 700 °C. DC resistivity of 77 Ωcm at higher annealing temperature obtained using a four point probe station. In order to prove the feasibility at high frequencies, a test structure consisting of a 50 Ω transmission line and capacitors with 50 × 50 μm electrode area were patterned on the films using electron beam lithography. The radio frequency (RF) properties were measured using aWiltron 37269Avector network analyzer andCascade Microtechon-wafer probes measured over a frequency range of 0.5 to 3 GHz. The dielectric constant, loss tangent and return loss, S11improve with the increment annealing temperature. The dielectric constant was found to be 18.8, with loss tangent of 0.02 at 1 GHz. These give a corresponding size reduction of ten times compared to conventional dielectrics, silicon nitride (Si3N4). These indicate that the material is suitable to be implemented as a new dielectric material for 1GHz MMIC applications.

A three-channel thermoelectric RF MEMS power sensor for GaAs MMIC applications

This paper presents an X-band three-channel thermoelectric radio frequency microelectromechanical systems (RF MEMS) power sensor with three inputs and one output, in order to measure the power with up to three RF signals. This power sensor is based on the principle of power–heat–voltage conversion and accomplished with the GaAs monolithic microwave integrated circuit (MMIC) technology. The three inputs are used to transmit RF signals over coplanar waveguide (CPW) lines and the one output collects the thermovoltage. To show good electromagnetic and thermal isolations, signal crosstalks for the three-input and one-output power sensor are quantified by the S-parameters simulation and the power handling measurement, respectively. In addition, the measured power sensor has resulted in three input reflection coefficients of less than −21.5dB for frequencies up to 12GHz. Experiments demonstrate the sensor has the good linearity of the power with respect to the thermovoltage at X-band, with sensitivities of about 53.1μVmW−1, 56.3μVmW−1, 58.9μVmW−1 for the three inputs at 12GHz, respectively.

A compact realization of composite low-pass filter for monolithic microwave integrated circuit applications

A compact realization of composite low-pass filter is presented in this article. The filter is realized using on-chip spiral inductors and metal–insulator–metal capacitors and features an attenuation pole near the cutoff frequency leading to a sharper attenuation response. As well, it offers good matching properties in the passband. Space-mapping-based algorithm is used in the design/optimization of spiral inductors toward achieving high quality factors at the filter cutoff frequency. The realization of the proposed filter is compact in size, suitable for monolithic microwave integrated circuit applications, and exhibit broad upper stopband frequency characteristics. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012. © 2012 Wiley Periodicals, Inc.

An improved passive inductor microwave performance on gallium nitride substrates using ion implantation technology

Recently, gallium nitride (GaN) substrates have been widely used in high-power monolithic microwave integrated circuit applications, which work because of the high breakdown voltage associated with the wider energy band-gap. The objective of this article is to investigate the spiral inductors that have been used to implant various ions on GaN substrates, demonstrated separately by N+, Mg+ and O+. The measured substrate resistance (R sub) results were 85 Ω and 360 Ω for undoped GaN substrates and N+ doped substrates, respectively. This ion implantation technology could substantially improve the substrate resistance and provide a higher quality factor value (Q-value) for spiral inductors. The low parasitic effect extracted by the scattering parameter (S-parameter) for various substrates indicated that the spiral inductor value can be applied stably at high frequency. Consequently, the high GaN substrate quality adopting high-isolation ion implantation technology, demonstrates its huge potential for high-power and high-efficiency amplifier applications.

3-D CMOS Circuits Based on Low-Loss Vertical Interconnects on Parylene-N

Parylene-N is used as a dielectric layer to create ultra low-loss 3-D vertical interconnects and coplanar waveguide (CPW) transmission lines on a CMOS substrate. Insertion loss of 0.013 dB for a 3-D vertical interconnect through a 15-¿ m-thick parylene-N layer and 0.56 dB/mm for a 50-¿ CPW line on the parylene-N layer (compared to 1.85 dB/mm on a standard CMOS substrate) are measured at 40 GHz. L-shaped, U-shaped, and T-junction CPW structures are also fabricated with under passes that eliminate the discontinuities arisen from the slot-line mode and are characterized up to 40 GHz. A 3-D low-noise amplifier using these post-processed structures on a 0.13-¿m CMOS technology is also presented along with the investigation of parasitic effects for accurate simulation of such a 3-D circuit. The 3-D circuit implementation reduces the attenuation per unit length of the transmission lines, while preserving the CMOS chip area (in this specific design) by approximately 25%. The 3-D amplifier measures a gain of 13 dB at 2 GHz with 3-dB bandwidth of 500 MHz, noise figure of 3.3 dB, and output 1-dB compression point of +4.6 dBm. Room-temperature processing, simple fabrication, low-loss performance, and compatibility with the CMOS process make this technology a suitable choice for future 3-D CMOS and BiCMOS monolithic microwave integrated circuit applications that currently suffer from high substrate loss and crosstalk.

A Compact Ka-Band Planar Three-Way Power Divider

A Ka-band planar three-way power divider which uses the coupled line instead of the transmission line is proposed to reduce chip size. The proposed planar topology, different from the conventional Wilkinson power divider, is analyzed and can provide not only compact but also dc block characteristics, which are very suitable for monolithic microwave integrated circuit applications. The divider implemented by a pHEMT process shows an insertion loss less than 5.1 dB and an output isolation better than 17 dB. A return loss less than 18 dB and a phase difference of 4.2deg at 30 GHz can be achieved. Finally, good agreements between the simulation and experimental results are shown.

Reactive ion etching technique for via-hole applications in thick GaAs wafers

The dry etching technique has been developed to etch via holes through a 5-mil-thick GaAs wafer by rf power and reactive gas pressures in a reactive ion etching system. The etching parameters are optimized for a slope profile suitable for power field effect transistors and monolithic microwave integrated circuit applications. The selectivity between GaAs and photoresist and the average etching rate can be higher than 30 and 1.1μm∕min, respectively. Furthermore, the slope angle measured from the vertical is larger than 11°, which is well suited for a thick GaAs via-hole etching process. Before the metal for the via-hole substrate is sputtered, the wet chemical etching solution based on HCl–H2O2∕H2O at room temperature is used to smooth the sidewall for a better connection. To probe these source pads, the via-hole resistances of the pseudomorphic high electron mobility transistors (PHEMTs) are measured to be less than 0.5Ω with more than 97.2% yield in a 4in. diameter GaAs wafer. It is found that the rf performance for low-noise and power PHEMTs can be further improved.

Hybrid ring coupler for W-band MMIC applications using MEMS technology

The hybrid ring coupler was designed and fabricated on a GaAs substrate using surface micromachining techniques, which adopted dielectric-supported air-gapped microstrip line (DAML) structure. The fabrication process of DAML is compatible with the standard monolithic microwave integrated circuit (MMIC) techniques, and the hybrid ring coupler can be simply integrated into a plane-structural MMIC. The fabricated hybrid ring coupler shows wideband characteristics of the coupling loss of 3.57 /spl plusmn/ 0.22dB and the transmission loss of 3.80 /spl plusmn/ 0.08dB across the measured frequency range of 85 to 105GHz. The isolation characteristics and output phase differences are -34dB and 180/spl plusmn/1/spl deg/, at 94GHz, respectively.

A novel microstrip-line structure employing a periodically perforated ground metal and its application to highly miniaturized and low-impedance passive components fabricated on GaAs MMIC

In this study, highly miniaturized and low-impedance on-chip passive components were developed using a novel microstrip-line structure employing periodically perforated ground metal (PPGM) on a GaAs monolithic microwave integrated circuit (MMIC). The proposed microstrip-line structure exhibited a much lower characteristic impedance and shorter guided wavelength than the conventional structure. Using the microstrip line with PPGM, a highly miniaturized rat-race and branch-line coupler with low-port impedances were developed for K/Ka-band MMIC applications. The miniaturized rat-race and branch-line coupler were fabricated on a GaAs substrate with a height of 100 /spl mu/m, and their sizes were 0.375 and 0.25 mm/sup 2/, respectively, which are less than 10% of the sizes of conventional ones. The miniaturized rat-race and branch-line coupler exhibited good RF performances from 20 to 30 GHz. In addition, in this study, highly miniaturized on-chip filters and biasing components were also realized using the microstrip-line structure with PPGM. The above results indicate that a microstrip-line structure with PPGM is a promising candidate for applications to highly miniaturized passive components on GaAs MMICs, and it will enable the development of fully integrated MMICs, including all passive components.

Bilan des saignements d'origine digestive par microcapsule

Following the introduction of metamorphic high electron mobility transistors (MHEMTs) 30 years back, there has been a rapid growth in their use in advanced MMIC (monolithic microwave integrated circuit) and TMIC (Terahertz monolithic integrated circuit) applications in sub-millimetre wave (S-MMW) and terahertz (THz) frequency regime. Undoubtedly, they are capable of making a great impact in applications such as deep space, cryogenic, biomedical instrumentation, military, high speed communication networks etc, in the years to come. This review article not only studies the progress of depletion mode (D-Mode), enhancement mode (E-Mode) type MHEMTs in the last 30 years, extensively but also critically and systematically analyzes the fabrication challenges, reliability issues and their use in cryogenic fields. Yet another highlight is that the work also carefully examines the utility of MHEMTs in deep space, biomedical, scientific, military, communication areas and so forth.

A new class of miniature quadrature couplers for MIC and MMIC applications

AbstractA new class of miniature quadrature couplers suitable for microwave integrated circuits (MICs) and monolithic microwave integrated circuits (MMICs) are presented. The proposed couplers have some advantages compared to conventional types, such as smaller size, no harmonic response, and wide stop‐band characteristics. Two 3‐dB quadrature couplers at two different frequencies, 0.9 and 10 GHz have been designed and simulated. The coupler designed at 900 MHz has been fabricated on Duroid substrate with microstrip technology. Compared to the standard quadrature coupler more than 65% area savings, has been achieved, and the first higher‐order response appears at 5.8 GHz. The measured results show good agreement with theoretical prediction. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 215–219, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10421

Branch-line couplers using unequal line lengths

General solutions for branch-line couplers using different line lengths are provided in this paper. Explicit expressions are derived with which a hybrid with any given power division ratio can be designed. In the design, one of the characteristic impedances or lengths of the branches can be chosen arbitrarily to suit a given design specification. This approach brings flexibility in choosing the characteristic impedances or the lengths of the branches, and is helpful especially in monolithic-microwave integrated-circuit applications where restrictions imposed on microstrip transmission lines do not allow the use of conventional branch-line couplers employing quarter-wave-long lines. However, the resultant bandwidth is narrower compared to that of the conventional coupler.

Comparison of frequencyresponses of spiral inductors with different figures

The results of a comprehensive investigation into thecharacteristics of inductors fabricated by the GaAs monolithic microwaveintegrated circuit (MMIC) process arepresented. Various spiral inductors with different figures werefabricated and measured, and their frequency responses wereinvestigated. The S-parameter optimization was used to estimatethe lumped elements of the pi-equivalent circuit model ofinductors. The simulated results indicate that the qualityfactor (Q) of the inductor is dominated by loss in the metalstrip at lower frequency, and loss introduced by the substratedissipation tends to dominate the performance at higherfrequency. In addition, the inductance affects the Q value over thewhole frequency range. The series resistance of a circularinductor is about 10% smaller than that of a square inductorwith the same diameter. The reduction of the diameter and turnsdecrease the Q value at lower frequency, but the Q value isincreased at higher frequency since the rapid drop ofinductance induces the decrease of Qmet and theincrease of Qsub. The wide metal width increasesQmet by the reduction of the resistance and theincrease of inductance. To guide the design of inductor, thedesign formula was established based on experimental results. Itis expected that when the geometrical dimension is selected theformula will help us to predict the properties of inductors easily.Among the three types of inductor, the circular and octagonalinductors have the higher quality factor and the lower loss,which implies that these types of inductor are appropriate forGaAs MMIC applications.

Small H-shaped antennas for MMIC applications

A small short-circuited H-shaped GaAs monolithic microwave integrated circuits (MMICs) patch antenna is presented. Resonant at 5.98 GHz, it is the lowest frequency MMIC patch antenna reported that we are aware of and is intended for short-range communications (e.g., vehicular). Initial experimental and theoretical characterization of the proposed structure has been carried out on soft microstrip substrates. It has been shown that the size of an H-shaped patch antenna can be reduced to as low as one tenth of that of a half wavelength patch antenna resonant at the same frequency, saving valuable substrate space. The resonance frequency, radiation patterns and gain have been investigated. Ground plane truncation effects, which are important for MMIC applications, have been examined using the finite-difference time-domain (FDTD) method.

Design of coplanar waveguide multilayer square spiral inductors for monolithic microwave integrated circuits

A square indicator using multilayer coplanar waveguide transmission lines on a GaAs fabricated by using monolithic microwave integrated circuits (MMIC) technology is presented. The polyimide layer formation, curing and dry etching processes are used in an attempt to obtain high quality dielectric layers suitable for MMIC applications. The experimental fabrication progress provides two metal layers with two polyimide spacer dielectric layers. A brief overview of the electromagnetic design process is included. The performance of the proposed spiral inductor is investigated experimentally and with electromagnetic simulations (Sonnet em) up to 20 GHz using RF-on-water measurements. A very good agreement is achieved, despite the highly three-dimensional nature of the structure. ©1999 John Wiley & Sons, Inc. Int J RF and Microwave CAE 9: 86–92, 1999

Low loss multilayer microstrip line for monolithic microwave integrated circuits applications

Low loss multilayer microstrip line for monolithic microwave integrated circuits applications