GaAs MMIC Research Articles

MIM capacitor-related early-stage field failures

Several early-stage field failures in systems mounting GaAs MMICs were specifically related to MIM capacitor failures.Failure analysis, in turn, classified the failed cases into three main categories, all referred to some weakness in the technological process.The relevant point is that such weak devices can reach the field at such a large scale, despite the very well known nature of their weakness.Ineffective screening at the Manufacturer’s plant is indicted for the problem.Lifetime prediction is attempted, on the user side, based on the detectability of the weak population.

A 35 GHz wireless millimeter-wave power sensor based on GaAs micromachining technology

A novel MEMS wireless millimeter-wave power sensor based on GaAs MMIC technology is presented in this paper. The principle of this wireless millimeter-wave power sensor is explained. It is designed and fabricated using MEMS technology and the GaAs MMIC process. With the millimeter-wave power range from 0.1 to 80 mW, the sensitivity of the wireless millimeter-wave power sensor is about 0.246 mV mW−1 at 35 GHz. In order to verify the power detection capability, this wireless power sensor is mounted on a PCB which influences the microwave performance of the CPW-fed antenna including the return loss and the radiation pattern. The frequency-dependent characteristic and the degree-dependent characteristic of this wireless power sensor are researched. Furthermore, in addition to the combination of the advantages of CPW-fed antenna with the advantages of the thermoelectric power sensor, another significant advantage of this wireless millimeter-wave power sensor is that it can be integrated with MMICs and other planar connecting circuit structures with zero dc power consumption. These features make it suitable for various applications ranging from the environment or space radiation detection systems to radar receiver and transmitter systems.

A novel MEMS double-channel microwave power sensor based on GaAs MMIC technology

A novel MEMS double-channel microwave power sensor based on GaAs MMIC technology is presented in this paper. Compared with the traditional thermoelectric microwave power sensor, a cantilever beam is introduced and monolithically integrated as a capacitive microwave power sensor to enhance the measurement range and improve the overload capacity. The low microwave power is detected by the thermoelectric microwave power sensor, and the high microwave is detected by the capacitive microwave power sensor. The models of output voltage and capacitance change are built, and the cantilever beam is researched. This microwave power sensor is designed and fabricated using MEMS technology and GaAs MMIC process. With the microwave power range from 0.1 to 100mW, the sensitivity of thermoelectric microwave power sensor is about 0.117, 0.109 and 0.096mV/mW at 8, 10 and 12GHz, respectively. With the microwave power range from 100 to 200mW, the sensitivity of capacitive microwave power sensor is about 0.027, 0.024 and 0.022fF/mW at 8, 10 and 12GHz, respectively. Furthermore, in addition to enhanced measurement range and improved overload capacity, another significant advantage of this MEMS microwave power sensor is that it can be integrated with MMICs and other planar connecting circuit structures with zero dc power consumption.

The MIMIC Program—A Retrospective

It has now been more than a quarter of a century since the U.S. Department of Defense (DoD) began its microwave and millimeter-wave monolithic integrated circuits (MIMIC) program. During that time, the Cold War ended and, as a result, there was a dramatic consolidation of defense companies. Many engineers, scientists, and others who participated in the program have changed companies, changed jobs, retired and, in some cases, died. The legacy of the program, however, remains: the establishment of the capabilities, infrastructure, and knowledge necessary to design and produce GaAs MMICs for nearly any application with high yield, at low cost, and possessing the specific performance and reliability characteristics required for their use in a huge number of system applications, both military and commercial [1][3]. This, in turn, has resulted in the United States' becoming the world leader in GaAs MMIC technology, a position that it still holds. The program played a major role in disproving the once popular statement that “GaAs is the material of the future and always will be.” This article describes the beginnings of the program and the strategy it used to achieve its goals. It also summarizes what has been accomplished and offers some advice based on the experience gained over the course of the program.

Modeling and design of a capacitive microwave power sensor for X-band applications based on GaAs technology

In the work, modeling and design of a capacitive microwave power sensor employing the MEMS plate with clamped–clamped and free–free edges are presented. A novel analytical model of the sensor is established in detail. Through the function of mode shapes presented, the natural frequency can be solved by the Rayleigh–Ritz method. And based on the generalized coordinate introduced, the displacement of the plate with the irradiation of microwave power can be solved. Furthermore, the sensitivity for the power is also derived. Then the detailed consideration of the design and simulation of the microwave characteristic of the sensor are also presented. The linearly graded ground planar in the coplanar waveguide is employed to avoid step discontinuity. The fabrication process is compatible with GaAs MMIC technology completely, also described in detail. The measurement of the proposed sensor indicates a sensitivity of 7.2 fF W−1 and superior return and insertion losses (S11 and S21), less than −22.16 dB and −0.25 dB, respectively, up to 12 GHz, suggesting that it can be available for microwave power detecting in the X-band frequency range.

An 8–12 GHz microwave frequency detector based on MEMS power sensors

An 8–12 GHz microwave frequency detector is presented, which is based on MEMS power sensors, by sensing the phase delay of two separated signals in two different tracks. The phase delay, proportional to frequency of the input microwave signal, leads to variation of the output power. Two different kinds of MEMS power sensors, a thermoelectric microwave power sensor and a MEMS capacitive power sensor, are adopted to measure the variation. The former is used for measuring the lower power while the latter for the higher one. The presented detector has been designed, optimized and fabricated successfully using the GaAs MMIC process. For the microwave signals of 10, 15 and 20 dBm, the measured result shows that the output thermovoltage decreases with the frequency based on the thermoelectric microwave power sensor and sensitivities of the detector better than 0.033, 0.110 and 0.343 µV MHz−1 are measured, respectively. Furthermore, the sensitivity of detector is directly proportional to the power of the input microwave signal. For the microwave signals of 24 dBm, the measured result shows that the capacitance decreases with the frequency based on the MEMS capacitive power sensor and the sensitivity of 0.013 fF MHz−1 is measured. The frequency measurement demonstrates the validity of the presented design.

GaAs MMIC fabrication for the RF MEMS power sensor with both detection and non-detection states

This paper presents the GaAs MMIC fabrication for the coupled RF MEMS power sensor with an impedance matching structure for improving the microwave performance, a capacitance compensating structure for obtaining the wideband response, and two shunt capacitive MEMS switches for achieving the conversion of the detection and non-detection state. In the fabrication process, we focus on discussing three key techniques of the fabrication such as the release of the MEMS membrane and switches, the protection of thermopiles and the process of the backside cavity, and propose the effects of these techniques on the power sensor. The validity of the fabrication is analyzed by the experiments, with the reflection and insertion losses of less than −17dB and 0.8dB in the detection state as well as that of less than −19dB and 0.6dB in the non-detection state, and the good power handing capability. Furthermore, the measured resistance of the thermopiles of the power sensor is about 172kΩ, which corresponds to the calculated signal-to-noise ratio of 2.5×106W−1.

High-Directivity Enhancement With Passive and Active Bypass Circuit Techniques for GaAs MMIC Microstrip Directional Couplers

This paper describes monolithic microwave integrated circuit microstrip directional couplers based on a new directivity enhancement technique. This technique utilizes a bypass circuit-a phase shifter and an attenuator-placed between the coupling and isolation ports to cancel out backward wave leakage to the coupling port, thereby enhancing directivity of the couplers. The bypass circuit can be implemented with a simple passive LCR circuit or an active heterojunction bipolar transistor (HBT) phase-inversion attenuation circuit. Edge-coupled-type microstrip spiral couplers using the passive and active bypass circuits were fabricated in a GaAs HBT process. Measurements are as follows. The coupler with the passive LCR bypass circuit delivers a -21-dB coupling factor and a 0.14-dB insertion loss (IL) at 2.6 GHz while keeping enhanced directivity of more than 30 dB with a 23.1% relative bandwidth. This corresponds to more than 21-dB improvement of directivity at the same frequency, compared to the coupler without the bypass circuit. For the coupler with the active attenuator, a peak directivity of 46 dB and more than 30-dB directivity with a 120% relative bandwidth are achieved while a -21-dB coupling factor and a 0.13-dB IL are delivered at 2 GHz. Additional measurements of HBT power detectors integrated with the couplers show that the couplers with passive and active bypass circuits can suppress detection errors of less than ±0.20 and ±0.10 dB, respectively, under 4:1 voltage standing-wave ratio load mismatching conditions, thus proving the effectiveness of the bypass techniques.

An 8–18 GHz broadband high power amplifier

An 8–18 GHz broadband high power amplifier (HPA) with a hybrid integrated circuit (HIC) is designed and fabricated. This HPA is achieved with the use of a 4-fingered micro-strip Lange coupler in a GaAs MMIC process. In order to decrease electromagnetic interference, a multilayer AlN material with good heat dissipation is adopted as the carrier of the power amplifier. When the input power is 25 dBm, the saturated power of the continuous wave (CW) outputted by the power amplifier is more than 39 dBm within the frequency range of 8–13 GHz, while it is more than 38.6 dBm within other frequency ranges. We obtain the peak power output, 39.4 dBm, at the frequency of 11.9 GHz. In the whole frequency band, the power-added efficiency is more than 18%. When the input power is 18 dBm, the small signal gain is 15.7 ± 0.7 dB. The dimensions of the HPA are 25 × 15 × 1.5 mm3.

A broadband GaAs MMIC frequency doubler on left-handed nonlinear transmission lines

A broadband frequency doubler using left-handed nonlinear transmission lines (LH NLTLs) based on MMIC technology is reported for the first time. The second harmonic generation on LH NLTLs was analyzed theoretically. A four-section LH NLTL which has a layout of 5.4 × 0.8 mm2 was fabricated on GaAs semi-insulating substrate. With 20-dBm input power, the doubler obtained 6.33 dBm peak output power at 26.8 GHz with 24–43 GHz −6 dBm bandwidth. The experimental results were quite consistent with the simulated results. The compactness and the broad band characteristics of the circuit make it well suit for GaAs RF/MMIC application.

Research on sensitivity characteristic of indirectly-heated type thermopile power sensor

The relationship of the sensitivity characteristic of the indirectly-heated type thermopile power sensor with the distance between the resistor and the thermopile is researched in this reported work. The sensors are designed and fabricated using the GaAs MMIC process with zero DC power consumption. The sensors are measured in the frequency up to 30 GHz within 100 mW range. The sensitivity at 10 GHz is about 0.12, 0.13, 0.12, 0.10, 0.09 and 0.08 mV/mW when the distance is set to 5, 10, 15, 20, 30 and 40 µm, respectively. The key significance of this work is that the relationship of the sensitivity characteristic with the distance is re-understood and researched quantitatively.

Sensitivity of MEMS microwave power sensor with the length of thermopile based on Fourier equivalent model

A Fourier equivalent model is introduced to research the thermal transfer behavior of a terminating-type MEMS microwave power sensor. The fabrication of this MEMS microwave power sensor is compatible with the GaAs MMIC process. Based on the Fourier equivalent model, the relationship between the sensitivity of a MEMS microwave power sensor and the length of thermopile is studied in particular. The power sensor is measured with an input power from 1 to 100 mW at 10 GHz, and the measurement results show that the power sensor has good input match characteristics and high linearity. The sensitivity calculated from a Fourier equivalent model is about 0.12, 0.20 and 0.29 mV/mW with the length at 40, 70 and 100 μm, respectively, while the sensitivity of the measurement results is about 0.10, 0.22 and 0.30 mV/mW, respectively, and the differences are below 0.02 mV/mW. The sensitivity expression based on the Fourier equivalent model is verified by the measurement results.

X-band coplanar Wilkinson power divider based on GaAs MMIC technology

An X-band coplanar Wilkinson power divider based on GaAs MMIC technology is proposed. The power divider is designed at 10 GHz and simulated using HFSS, and simulated results show that it has reflection loss of less than −16.5 dB and insertion loss of less than −3.6 dB. Measured results show that the divider has reflection loss of less than −15.0 dB and insertion loss of less than −3.5 dB. Experimental results agree well with simulated results.

A voltage source model on thermoelectric power sensor based on MEMS technology

In order to achieve monolithic integration of thermoelectric power sensor and its amplification system and improve the measurement accuracy of microwave power, a voltage source model is researched in this paper. And the thermoelectric power sensor is designed and fabricated using MEMS technology and GaAs MMIC process. It is measured in the X-band (8–12 GHz) with the input power in 100 mW range. When the input microwave power is at 10, 50 and 100 mW, respectively, the frequency dependent coefficient k1 is −0.073, −0.39 and −0.82 mV/GHz, respectively. The sensitivity coefficient k2 is 0.311, 0.303, 0.293, 0.284 and 0.279 mV/mW at 8, 9, 10, 11 and 12 GHz, respectively, and has an excellent linearity. Based on the voltage source model, the feedback coefficient of its amplification system is set to 0.0078 × Pin to compensate the loss power caused by frequency dependent characteristic. In addition to miniaturization and low cost, an advantage using this model is significantly improved measurement accuracy.

A GaAs MMIC-based coupling RF MEMS power sensor with both detection and non-detection states

This paper first presents the detection and non-detection function of an inline RF MEMS power sensor by employing two shunt capacitive MEMS switch structures. It solves a problem that regardless of whether the power sensor needed to detect the power, a certain microwave power will always be detected, which results in the unnecessary power loss. This power sensor is based on sensing a certain percentage of the incident microwave power coupled by a MEMS membrane. The effect of an impedance matching structure for improving microwave characteristics, a capacitance compensating structure for obtaining the wideband response, and the two shunt capacitive MEMS switch structures for achieving both states conversion together associated in this sensor, on the performance of the power sensor is proposed in this paper, and verified by the simulation and measurement. This power sensor offers the compatible capability with GaAs MMIC technology. In the detection state, experiments demonstrate that the design of the improved power sensor has resulted in the reflection loss of less than −17 dB, the insertion loss of less than 0.8 dB, and the flatness of the frequency response at X-band. And a sensitivity of more than 36 μV mW −1 and a resolution of 0.316 mW are obtained at 10 GHz under the normal ambient temperature. Yet in the non-detection state, the design has resulted in the reflection loss of less than −19 dB and the insertion loss of less than 0.6 dB. The measured actuation voltage of MEMS switches is about 42 V.

X-band microwave phase detector manufactured using GaAs micromachining technologies

A novel integrated X-band microwave phase detector fabricated using GaAs micromachining technologies is presented in this paper. The proposed phase detector is composed of a power combiner and a thermoelectric microwave power sensor based on the Seebeck effect. The power sensor is used to sense the power of the combined signal, which is proportional to the phase difference. This detector is compatible with GaAs MMIC technology. Since it is entirely composed of passive devices, zero dc power consumption is realized with a simple structure. Different power levels from 2 to 23 dBm at 10 GHz are applied to the detector, and the measured result shows a function of 1 + cos φ (φ is the phase difference). Good linearity appears from about 45° to 135°, and sensitivities are 58.57, 27.86, 14.52 and 7.22 µV deg−1 with 23, 20, 17 and 14 dBm signal applied, respectively. Frequency characteristics are measured at three different phase shifts, 0°, 90° and 180°, and the phase detector shows the frequency detection capability in principle, if a proper phase shifter is adopted.

Thermoelectric power detector for microwave application at X-band based on GaAs MMIC technology

A thermoelectric power detector is proposed to integrate with MMICs and other planar connecting circuit structures at X-band (8-12 GHz). The thermoelectric power detectors without and with the tapered line are designed to use 50 Ω coplanar waveguides as commonly applied in MMIC devices. The sensitivity without the tapered line is about 0.224, 0.211, and 0.202 mV/mW at 8, 10, and 12 GHz, respectively. For the power detector with the tapered line, the sensitivity is about 0.326, 0.311, and 0.295 mV/mW, and it increases averagely about 46% compared with that without the tapered line. This reported work is focused on developing microwave power detectors to be integrated with MMICs and other planar connecting circuit structures.

COPLANAR RING DIVIDER WITH WIDEBAND HIGH ISOLATION PERFORMANCE

In this letter, the design and measurement of a new ring power divider exhibiting wideband high isolation is presented. Coplanar techniques are used to achieve a compact and truly uniplanar design. The design is demonstrated by a prototype, operating at K- band, that has been monolithically fabricated using a GaAs MMIC process with airbridge technology. The measured insertion loss is 0.6dB at the center design frequency of 25GHz. The output port isolation is better than 20dB across a wide bandwidth from 10MHz to 50GHz. The output amplitude and phase balance is within §0:5dB and §2 - , respectively, in the bandwidth from 10MHz to 43GHz.

An Ultra-Wideband Balun Using Multi-Metal GaAs MMIC Technology

In this paper, we demonstrate an ultra-wideband MMIC Marchand balun that utilizes a two-layer benzocyclobutene (BCB) GaAs MMIC process with a total of 4 metal layers. This multi-metal technology is built upon a standard GaAs HEMT technology with full compatibility. The fabricated balun achieved an approximately 11:1 bandwidth from 2 to 22 GHz, with less than 3-degree maximum phase imbalance, and less than 1 dB maximum amplitude imbalance. To our knowledge, this is the largest bandwidth ratio ever reported for an MMIC Marchand balun.

60 GHz radio front end demonstrator with Quality of Service

A 60 GHz front end demonstrator with Quality of Service capabilities is presented. It consists of transmitter and receiver front ends with planar beamforming antennas. The antennas can select between four different beams using a Rotman lens, enabling different scenario configurations. The transmitter and receiver are built using commercial GaAs MMIC components and a commercial substrate. The demonstrator is capable of non-line-of-sight communication in a scenario using a single reflection on a plane, making possible the link even if a body is blocking the direct signal path. This is done by selecting a particular antenna beam at the transmitter and receiver. The demonstrator can be used in channel investigations for 60 GHz applications such as wHDMI.