GaAs Monolithic Microwave Integrated Circuit Research Articles

Study of complete interconnect reliability for a GaAs MMIC power amplifier

ABSTRACTBy combining the finite element analysis (FEA) and artificial neural network (ANN) technique, the complete prediction of interconnect reliability for a monolithic microwave integrated circuit (MMIC) power amplifier (PA) at the both of direct current (DC) and alternating current (AC) operation conditions is achieved effectively in this article. As a example, a MMIC PA is modelled to study the electromigration failure of interconnect. This is the first time to study the interconnect reliability for an MMIC PA at the conditions of DC and AC operation simultaneously. By training the data from FEA, a high accuracy ANN model for PA reliability is constructed. Then, basing on the reliability database which is obtained from the ANN model, it can give important guidance for improving the reliability design for IC.

Investigation of Wafer Level Packaging schemes for 3D RF interposer multi-chip module

Abstract Very small RF modules can be realized through heterogenous integration of GaAs MMIC (monolithic microwave integrated circuit) onto a low loss Si sub-mount, with high density routing lines realized by advanced patterning. In this paper we investigate how to integrate MMIC active devices on GaAs with the RF passives produced on an interposer, using Si wafer process technology. High resistive Silicon substrates are required to minimize RF losses. The interposer is thinned below 100 μm to reveal Cu TSVs from the back of the interposer, while the front side is covered entirely with a silicon capping wafer for shielding the device. We compare different wafer level packaging approaches for producing the low RF-loss interposers, and populating them using die-to-die (D2D) or die-to-wafer (D2W) bonding of the MMIC components, followed by wafer level encapsulation. Two D2W approaches are compared, in the first approach the D2W mounting and the encapsulation happens before the Si interposer is thinned for TSV reveal. To avoid damage during thinning of the wafer, thicker substrates with deeper TSV of 150 μm or more are required. In a second approach, the thinning of the interposer is done prior to the mounting. Initial electrical data showed that the approach yielded proper RF performance, but further yield optimization is required.

N⁺ GaAs/AuGeNi-Au Thermocouple-Type RF MEMS Power Sensors Based on Dual Thermal Flow Paths in GaAs MMIC.

To achieve radio frequency (RF) power detection, gain control, and circuit protection, this paper presents n+ GaAs/AuGeNi-Au thermocouple-type RF microelectromechanical system (MEMS) power sensors based on dual thermal flow paths. The sensors utilize a conversion principle of RF power-heat-voltage, where a thermovoltage is obtained as the RF power changes. To improve the heat transfer efficiency and the sensitivity, structures of two heat conduction paths are designed: one in which a thermal slug of Au is placed between two load resistors and hot junctions of the thermocouples, and one in which a back cavity is fabricated by the MEMS technology to form a substrate membrane underneath the resistors and the hot junctions. The improved sensors were fabricated by a GaAs monolithic microwave integrated circuit (MMIC) process. Experiments show that these sensors have reflection losses of less than −17 dB up to 12 GHz. At 1, 5, and 10 GHz, measured sensitivities are about 63.45, 53.97, and 44.14 µV/mW for the sensor with the thermal slug, and about 111.03, 94.79, and 79.04 µV/mW for the sensor with the thermal slug and the back cavity, respectively.

Ka‐band RF MEMS capacitive switch with low loss, high isolation, long‐term reliability and high power handling based on GaAs MMIC technology

This study presents a Ka-band radio frequency (RF) micro electro mechanical systems (MEMS) capacitive switch with low loss, high isolation, long-term reliability and high power handling based on GaAs microwave monolithic integrated circuit (MMIC) technology. In this design, a T-matching structure is employed to realise impendence matching at ‘up-state’ by modifying the dimensions of centre signal line. Thus, the reflection loss and insertion loss are improved effectively. Measurement results show that in ‘up-state’ position, the input reflection coefficient (S11) is less than −20.4 dB with the forward transmission coefficient (S21) of better than −0.27 dB at Ka-band (27–40 GHz). At ‘down-state’, the switch is designed in a state of self-resonance to obtain high isolation. The measured isolation is better than 20 dB over Ka-band and can reach 35 dB at its self-resonant frequency of 35 GHz. The measured actuation voltage is about 36 V. The measured lifetime is at least 5.76 × 107 cycles. The measured power handling capability can reach up to 39 dBm. The proposed compact RF MEMS capacitive switch possesses excellent performances in terms of low insertion loss, high isolation, long lifetime and high power handling capability.

Research on the Response Time of Indirect-Heating Microwave Power Sensor

This paper mainly presents the response time with different parameters to study the dynamic response characteristic of indirect-heating thermoelectric microwave power sensor in order to provide reference for numerous practical applications. The fabrication of thermoelectric power sensor is compatible with the microelectromechanical systems technology and GaAs microwave monolithic integrated circuit process. An equivalent model of a typical thermoelectric power sensor is proposed to briefly analyze the thermal time constant in cooling process and theoretically predicted trends are nearly in accordance with the measured fall time when the membrane has nearly the same length of the thermopile. Measurements indicate that the response time does not change obviously with the incident power and ambient temperature, and increases with the length of thermopile and distance between resistors and thermopile. When the length of thermopile is 100 μm and distance between resistors and thermopile is 10 μm, the rise time and fall time of power sensor under normal ambient temperature 300 K are 1.06 and 0.37 ms, respectively. Furthermore, the return loss and the output voltage are measured with a large incident power to characterize the performance and study the failure phenomenon of the power sensor. The obtained burn-out power of the power sensor is ~1.1 W.

High‐power up to 4 W characteristics of the capacitive microwave power sensor with grounded beam

The high-power up to 4 W characteristic of a capacitive microwave power sensor with grounded MEMS beam is investigated. This device is fabricated by GaAs MMIC (microwave monolithic integrated circuit) technology. Experimental results indicate that the sensitivity of power sensor gradually degenerates with input power increasing continually. The measurement results are divided into three regions: pre-saturated, saturated and over-saturated regions. The corresponding sensitivities are 0.95, 0.76 and 0.56 fF/W at 10 GHz, respectively. This effect is caused by the device's capacitive mismatch at high-power, and the modified formula is calculated in sections.

Formation of copper-based interconnects for GaAs monolithic microwave integrated circuits

Technological solutions are presented for forming interconnect metallization of GaAs monolithic microwave integrated circuits (MMICs) based on the W/Cu/WN x thin-film composition. A peculiarity of these solutions is that, for the first time, copper conductors with the surface completely surrounded by layers of diffusion barriers are created using the liftoff method traditionally employed for producing GaAs MMICs. Copper conductors 380 nm thick were deposited by E-beam evaporation, while the layers of planar and sidewall diffusion barriers based on W and WN x were sputtered. For successful formation of the sidewall diffusion barriers on the vertical surfaces of the copper conductors, the profile optimization of the photoresist mask was carried out. Modes of removing the photoresist mask are presented that enable effective elimination of the metallic “veils” formed on the vertical walls of the photoresist mask in the process of sputtering of diffusion barriers. The interconnects W/Cu/WN x were integrated into the manufacturing process of GaAs microwave low-noise amplifiers based on the pHEMT with 250 nm T-gates.

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.

An X‐band Wilkinson power divider and comparison with its miniaturization based on GaAs MMIC process

ABSTRACTThis article presents an X‐band Wilkinson power divider which is completely compatible with GaAs monolithic microwave integrated circuit (MMIC). The novelty is that, GaAs is chosen for the realization for substrate because of its excellent microwave performance, and Au is used to fabricate transmission lines and air bridges due to its good electric properties. The measured return loss of port 1 is about −32 dB at the center frequency of 9 GHz and less than −16 dB over X‐band. The insertion loss of port 2 and 3 is close to 3.3 dB at 8–12 GHz. The measured bandwidth for which the input return loss is less than −20 dB is about 3.2 GHz. For the miniaturized power divider, the measured return loss of port 1 is about −23 dB at the center frequency of 11 GHz and less than −13 dB over the band of 8–12 GHz. The measured insertion loss of port 2 and 3 is close to 3.5 dB over the X‐band. The measured bandwidth of the miniaturized divider is less than 1.6 GHz. Comparison between the Wilkinson power divider and the miniaturized one shows that the shorter the quarter‐wave transmission line is, the larger the impedance is. Meanwhile, the chip area reduction also leads to narrowed bandwidth of the power divider. The experiments demonstrate that the MMIC chip area of the power divider has been reduced by nearly 50% by capacitive loading, whereas the bandwidth is also narrowed by 50%. Therefore, the Wilkinson power divider applies to the situation if wide bandwidth is needed, while the miniaturized one is a better solution for small chip area. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:700–705, 2014

Design Aspects of an Antenna-MMIC Interface Using a Stacked Patch at 71–86 GHz

A bond-wire-free interconnection between monolithic microwave integrated circuit (MMIC) and antenna using a stacked patch configuration is investigated. An edge-fed patch on a gallium arsenide (GaAs) MMIC chip drives a patch antenna integrated in the lid of the MMIC package. The lid is formed using a liquid crystal polymer (LCP) substrate. The first implementation using a laminated multichip module (MCM-L) process is presented that covers the designated E-band spectrum for long-range wireless communications (71–86 GHz). Electromagnetic simulations and measurements of antenna radiation patterns agree well over the whole frequency range of interest. Important design aspects and manufacturing tolerances specific for the implementation of the interface in MCM-L millimeter-wave front-ends are presented. An alternative design is proposed for improved radiation patterns across the band.

Young's modulus and residual stress of MEMS gold beams based on the GaAs MMIC process

This paper proposes the theory, simulation, fabrication and measurements of Young's modulus and the residual stress of the GaAs monolithic microwave integrated circuit (MMIC)-based microelectromechanical systems (MEMS) gold beams. In this paper, some cantilever and bridge MEMS gold beams with different lengths are fabricated in order to measure Young's modulus and the residual stress, which is completely compatible with the GaAs MMIC process. In the measurement, the resonance method is utilized due to the non-destruction and the high accuracy. These measurements are analyzed using analytical beam theory. After the evaluation process, the accuracy of the measurement results is discussed.

A capacitive power sensor based on the MEMS cantilever beam fabricated by GaAs MMIC technology

In this paper, a novel capacitive power sensor based on the microelectromechanical systems (MEMS) cantilever beam at 8–12 GHz is proposed, fabricated and tested. The presented design can not only realize a cantilever beam instead of the conventional fixed–fixed beam, but also provide fine compatibility with the GaAs monolithic microwave integrated circuit (MMIC) process. When the displacement of the cantilever beam is very small compared with the initial height of the air gap, the capacitance change between the measuring electrode and the cantilever beam has an approximately linear dependence on the incident radio frequency (RF) power. Impedance compensating technology, by modifying the slot width of the coplanar waveguide transmission line, is adopted to minimize the effect of the cantilever beam on the power sensor; its validity is verified by the simulation of high frequency structure simulator software. The power sensor has been fabricated successfully by Au surface micromachining using polyimide as the sacrificial layer on the GaAs substrate. Optimization of the design with impedance compensating technology has resulted in a measured return loss of less than −25 dB and an insertion loss of around 0.1 dB at 8–12 GHz, which shows the slight effect of the cantilever beam on the microwave performance of this power sensor. The measured capacitance change starts from 0.7 fF to 1.3 fF when the incident RF power increases from 100 to 200 mW and an approximate linear dependence has been obtained. The measured sensitivities of the sensor are about 6.16, 6.27 and 6.03 aF mW−1 at 8, 10 and 12 GHz, respectively.

X‐Band GaAs mmic high power amplifier for transmitter space module

AbstractIn this letter, the design, realization, and test of an X‐band GaAs microwave monolithic integrated circuit high power amplifier (HPA) are reported.The HPA is designed in a two stage configuration to fully match a 50 Ω input and output impedance. Experimental results show that the HPA reaches an output power higher than 38 dBm with a gain higher than 17 dB and a ripple lower than 0.5 dB from 9 to 10.2 GHz frequency range. The power added efficiency is around 40%. The good level of performance and the low sensitivity to the environment temperature make this amplifier an excellent candidate for X band applications in phased array active antennas. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2633–2635, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27109

Micromachined GaAs MMIC-Based Spiral Inductors With Metal Shores and Patterned Ground Shields

This paper presents micromachined GaAs monolithic microwave integrated circuits (MMIC)-based radio frequency (RF) planar spiral inductors with metal shores (MS) and patterned ground shields (PGS). The inductors are fabricated using a GaAs MMIC process without any additional step. MS and PGS are located and inserted between the planar spiral inductors and the GaAs substrate respectively for depressing substrate losses. To further improve its performance, the backside substrate of each inductor is processed to form the membrane structure by the via-hole etching technology. Based on the parameter extraction about a single-ended method, the characteristics of two-type RF spiral inductors (3.5- and 4.5-turn) are investigated. The measured quality factor (Q) of 4 nH on-chip spiral MMIC inductors (4.5-turn) with MS and PGS are 13 at 5.8 GHz and 14.2 at 6.6 GHz, respectively. Measurement results demonstrate that the effects of MS and PGS on the Q of MMIC inductors have resulted in the improvement of about 6% and 15%, respectively, and on the inductance and the metal losses are almost constant in interested frequencies. These improved inductors applied to GaAs MMIC-based passive lowpass filters reduce insertion losses of the filters.

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 Novel Thermoelectric and Capacitive Power Sensor With Improved Dynamic Range Based on GaAs MMIC Technology

A novel thermoelectric and capacitive power sensor with improved dynamic range based on GaAs monolithic microwave integrated circuit (MMIC) technology is proposed in this letter. This power sensor is designed and fabricated using GaAs MMIC process and MEMS technology. A MEMS cantilever beam is introduced and monolithically integrated as a capacitive power sensor to improve the overload capacity and the dynamic range at the cost of sensitivity. The measurement results verify the role of the MEMS cantilever beam. Another advantage of this power sensor consists in compatibility with MMIC devices and other planar connecting circuit structures with zero dc power consumption.

A micromachined inline type microwave power sensor with working state transfer switches

A wideband 8–12 GHz inline type microwave power sensor, which has both working and non-working states, is presented. The power sensor measures the microwave power coupled from a CPW line by a MEMS membrane. In order to reduce microwave losses during the non-working state, a new structure of working state transfer switches is proposed to realize the two working states. The fabrication of the power sensor with two working states is compatible with the GaAs MMIC (monolithic microwave integrated circuit) process. The experimental results show that the power sensor has an insertion loss of 0.18 dB during the non-working state and 0.24 dB during the working state at a frequency of 10 GHz. This means that no microwave power has been coupled from the CPW line during the non-working state.

Wide-band radio frequency micro electro-mechanical systems switches and switching networks using a gallium arsenide monolithic microwave-integrated circuits foundry process technology

In this study, the authors present the designs and experimental results of radio frequency (RF) micro electro-mechanical systems (MEMS) switches and switching circuits for gallium arsenide (GaAs)-based monolithic microwave-integrated circuits (MMIC). The switches and switching networks [single-pole single throw (SPST), single-pole double throw and double-pole double throw] are fabricated using OMMIC&apos;s GaAs MMIC foundry process technology. Measured results for a wide-band SPST switch design show isolation better than 20 dB up to 80 GHz with impedance matching better than −15 dB and insertion loss below 1.6 dB. Such low-loss GaAs-based RF MEMS switches are also capable of sustaining a power level of more than 10 W (up to 41 dBm) at 1 and 4 GHz, respectively, during cold-switching cycling conditions. Finally, to highlight the possibilities and benefits of monolithic integration of such MEMS switches and active RF devices on the same GaAs substrate, we present the experimental results of a wide-band (i.e. more than 10–40 GHz) GaAs MEMS-enabled switched low-noise amplifier circuit.

GaAs MMIC 상에서 주기적 접지구조를 가지는 미앤더 선로에 관한 연구

In this study, highly miniaturized short-wavelength meander line employing eriodically patterned ground structure (PPGS) was developed for application to miniaturized on-chip passive component on GaAs MMIC (monolithic microwave integrated circuit). The meander line employing PPGS showed shorter wavelength and slow-wave characteristic compared with conventional meander line. The wavelength of the meander line employing PPGS structure was 17 % of the conventional meander line on GaAs MMIC. Due to its slow-wave structure, the meander line employing PPGS exhibited large propagation constant than conventional meander line, which resulted in larger phase shift and shunt inductance value. Above results indicate that the meander line employing PPGS is a promising candidate for application to a development of miniaturized on-chip RF components as well as inductor with a high inductance value on GaAs MMIC.

A 4 W K-band GaAs MMIC power amplifier with 22 dB gain

A 4 W K-band AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor (PHEMT) monolithic microwave integrated circuit (MMIC) high power amplifier (PA) is reported. This amplifier is designed to fully match for a 50 Ω input and output impedance based on the 0.15 μm power PHEMT process. Under the condition of 5.6 V and 2.6 A DC bias, the amplifier has achieved a 22 dB small-signal gain, better than a 13 dB input return loss, and 36 dBm saturation power with 25% PAE from 19 to 22 GHz.