GaAs MMIC Technology Research Articles

Reminiscing With Bob [MicroBusiness

I was fortunate to join a group that was at the forefront of GaAs MMIC technology in the early 1980s, at the Raytheon Research Division. At that time, there were a number of organizations leading the development of the technology. We had a friendly competition with research and advanced technology groups and a number of companies, including Texas Instruments, Hughes Aircraft, TRW, Westinghouse, HP, and GE in the United States. NEC in Japan, Plessey in the United Kingdom, and LEP in France also had groups working on the technology. I’m sure I’m forgetting some companies that were working in this area, to say nothing of the many government labs, academic institutions, and other organizations that made important contributions.

A Thermoelectric MEMS Microwave Power Sensor with Inline Self-Detection Function.

In this paper, the design, fabrication and measurement of a thermoelectric MEMS microwave power sensor with the terminal load inline self-detection function is proposed. The structure of the sensor mainly includes a coplanar waveguide, a thermopile, two terminal load resistors and two calibration resistors. In order to realize the inline self-detection function, the load and calibration resistors are designed to form a voltage divider circuit. The fabrication of this sensor is compatible with the GaAs MMIC technology. The on-chip performance is tested by using a microwave experimental platform. The measured reflection loss is less than −10 dB at 0.1–10 GHz. When the bias voltage is not applied, the sensitivity of the sensor is 47.39 μV/mW@5 GHz and 32.58 μV/mW@10 GHz, respectively, and when the bias voltage is applied, the sensitivity is 47.50 μV/mW@5 GHz and 32.73 μV/mW@10 GHz, respectively. The difference between the two cases is less than 0.5% at the same frequency, which indicates that whether or not to apply the bias voltage has little effect on the sensitivity. In addition, when the calibration resistance is increased from 50 to 100 Ω, the current flowing through the load resistance is decreased under the same bias voltage. Therefore, the DC power consumed on the load resistance will be significantly reduced. This makes the measured and theoretical results show better agreement, thus verifying the validity of the design.

A Compact Reconfigurable 1-D Periodic Structure in GaAs MMIC With Stopband Switching, Dual-Band Operation and Tuning Capabilities

This paper presents a systematic study of a compact and reconfigurable periodic structure in GaAs MMIC technology. Compactness is achieved by the introduction of spiral inductors in a conventional unit cell without disturbing the reactive loading mechanism. The proposed architecture exhibits a 28.3% wider stopband with 62.6% smaller footprint compared to a conventional structure. The compactness and bandwidth improvement in the proposed structure is explained with the help of dispersion and circuit analysis. The reconfigurability built into the design using PIN diodes allows stopband switching, dual-band operation and tuning capabilities with the mere use of a single reactive load in its unit cell. To the best of the authors knowledge, it is the first time a reconfigurable MMIC implementation is realized using the proposed structure or even the conventional design. As a guide to design, sensitivity analysis to filter performance is presented for important structure parameters. Switching element parasitics are discussed in two ways: firstly, with the design and measurement of structures with idealized switching conditions and in second, with the circuit and full-wave EM modelling of the finite periodic structure with the actual PIN diodes. The on-chip measurements of the fully reconfigurable filter show excellent agreement with simulations.

A novel gradient thermoelectric microwave power sensors based on GaAs MMIC technology

A novel gradient thermoelectric microwave power sensor is designed to improve the performance in this work. The thermocouples are designed with different lengths based on the thermal distribution of resistance. It is fabricated using GaAs MMIC technology, and it can be integrated with other planar circuit structures. The thermal distribution of the gradient thermoelectric microwave power sensor is simulated by ANSYS finite element software. The performances of the gradient thermoelectric microwave power sensors are measured. The result shows that return loss is better than − 25 dB at 8–12 GHz. It reveals that this structure has a low reflection loss and a good matching characteristic. The sensitivity is 9.6 mV/W@8 GHz, 8.7 mV/W@10 GHz and 7.8 mV/W@12 GHz, respectively, and an excellent linear relationship of the output voltage with the input microwave power is obtained. Therefore, this optimized design of thermocouples has certain reference value for thermoelectric microwave power sensors.

Design and characterisations of double-channel GaAs pHEMT Schottky diodes based on vertically stacked MMICs for a receiver protection limiter

A microwave receiver protection limiter circuit has been designed, fabricated and tested using vertically stacked GaAs MMIC technology. The limiter circuit with a dimension of 2.5 × 1.3 mm2 is formed by using double-channel AlGaAs/InGaAs pseudomorphic HEMT (pHEMT) Schottky diodes integrated with a low-loss V-shaped coplanar waveguide multilayer structure. The electrical parameter characteristics of the pHEMT Schottky diodes are presented including the C–V profile showing the presence of a double channel in the device layer structure. This unique feature can also be seen from the double-peak responses of the electron density as a function of the device layer width, which represent the high electron concentration at two different 2-DEG layers of the structure. An equivalent circuit model of pHEMT Schottky diodes is demonstrated showing good agreement with the measurement results. At zero-bias condition, the devices show high performance in diode detector applications with voltage sensitivities of more than 89 mV μW−1 at 10 GHz and at least 5.4 mV μW−1 at 35 GHz. The measurement results of the limiter circuit demonstrated the blocking of input power signals greater than 20 dBm input power at 3 GHz. To the best of our knowledge this is the first demonstration of the use of pHEMT Schottky diodes in microwave power limiter applications.

The research of indirectly-heated type microwave power sensors based on GaAs MMIC technology

In this work, the effect of the temperature and the humidity on the indirectly-heated type microwave power sensor is researched in order to extend its application field, and their mechanism is revealed. The fabrication of this microwave power sensor is divided into a front side and a back side processing using GaAs MMIC process and MEMS technology. One advantage of this microwave power sensor consists in compatibility with MMIC devices and other planar connecting circuits structures with zero dc power consumption. The measurement results show that the environment temperature has a significant effect on the performance of the indirectly-heated type microwave power sensor, and the humidity has a little effect on its performance. The temperature dependent coefficient is about 0.6 mV/(W K), which has an important reference value to other thermoelectric microwave power sensor. The reason is that the accuracy microwave power measurement will be realized as long as the environment temperature is tracked in the testing process.

Suspended Thermopile for Microwave Power Sensors Based on Bulk MEMS and GaAs MMIC Technology

In this letter, the effects of the suspended thermopile on the microwave and sensing performances of 0.01-30 GHz thermoelectric microwave power sensors are researched by experiments, in order to obtain the reasonable back-cavity dimension. The back-cavity underneath the thermopile is used to depress thermal losses of the power sensors and is fabricated using the bulk microelectromechanical systems process. Three thermoelectric power sensors with different suspension lengths of the thermopile are accomplished with the GaAs monolithic microwave integrated circuit technology. The three power sensors show good microwave matching impedance, with measured reflection losses of less than -21 dB up to 30 GHz. The good linearity between the input power and the output thermovoltages is obtained. When the suspension length of the thermopile is 20, 50, and 80 μm, the average sensitivity of these power sensors is 186.9, 238.9, and 286.0 μV/mW at 30 GHz, respectively. In addition, the relationships of the sensitivity with the microwave power and frequency are quantified under different suspension lengths of the thermopile.

An Inline RF Power Sensor Based on Fixed Capacitive Coupling for GaAs MMIC Applications

This letter proposes an inline RF power sensor based on fixed capacitive coupling for GaAs MMIC applications. In the design, a certain percentage of the input power coupled by a beam and sensed in a thermopile sensor, where the beam is not required to release to obtain a fixed capacitance for high-power levels and increase the dynamic range. This sensor offers the compatible capability with the GaAs MMIC technology. Measured reflection and insertion losses are <;-24.2 and 0.73 dB at X-band, respectively. Experiments demonstrate that this inline sensor exhibits good linearity of the output response from 1 to 200 mW, and results in the average sensitivity of ~29.5 μV/mW at 10 GHz. The sensitivity increases with the increase of the X-band frequency, with small measurement errors.

Research on temperature characteristic of thermoelectric microwave power sensors based on GaAs MMIC technology

The effect of temperature on thermoelectric microwave power sensors is researched in order to extend its application field. The fabrication of this microwave power sensor is divided into a front side and a back side processing using GaAs MMIC process and MEMS technology. The measurement results show that the temperature has a significant effect on the performance of thermoelectric microwave power sensors. The obtained temperature coefficient is about 0.488 mV/(W · K), which has an important reference value for the thermoelectric microwave power sensors. The reason is that the accuracy of microwave power measurement will be realised as long as the environment temperature is tracked.

A micro compact coplanar power divider at X-band with finite-width ground plane based on GaAs MMIC technology

A micro coplanar Wilkinson power divider at X-band on GaAs substrate is presented in this paper. The proposed power divider introduces a size reduction method, and the length of the transmission line is reduced to λ/8 (at 10 GHz). Since the two segments of the two edge coupled quarter-wave asymmetric coplanar striplines (ACPSs) with finite-width ground plane are closed to each other, their characteristic parameters, such as characteristic impedance and attenuation coefficient, are obtained using the quasi-static conformal mapping technique (CMT) of coupled coplanar waveguide (CCPW) with finite-width ground plane. S-parameters for the power divider are deduced in the case of quasi-static TEM even–odd mode. The fabrication process is compatible with the GaAs MMIC process. The measured S-parameters are compared with the simulated results of HFSS v.11 and the calculated results of TEM even–odd analysis. Simulated results show that it has reflection loss less of 16.5 dB and insertion loss less of 3.6 dB. Measured results show that the divider has reflection loss less of 15.0 dB and insertion loss less of 3.5 dB. Compared with conventional Wilkinson power divider, the length of the power divider is shortened from 2,620 to 1,570 μm.

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.

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 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.

A coupling RF MEMS power sensor based on GaAs MMIC technology

A wideband 8–12 GHz inline RF MEMS power sensor that is based on sensing a certain percentage of the incident microwave power coupled by a MEMS membrane is presented, and the sensor is accomplished with GaAs MMIC technology. In order to improve microwave characteristics and the frequency response of the output at X-band, an impedance matching structure and a capacitance compensating structure are proposed in the paper. The design of the power sensor with the improved structures has resulted in the measured reflection loss of the sensor less than −17 dB, the insertion loss less than 0.8 dB, and the flatness of the frequency response at X-band. A sensitivity of more than 26 μV mW −1 and a resolution of 0.316 mW are obtained at 10 GHz under the normal ambient temperature. The experiment demonstrates the immediate effect of the modulation depth under amplitude modulation (AM) signals on the sensitivity of the sensor. In addition, the measured mechanical resonant frequency ( f o) of the MEMS membrane of the sensor is 110 kHz. The measured results show that the intermodulation (IM) power for Δ f = 80 kHz, P 1 = P 2 = 10 dBm of the signals is less than −52 dBm, and the input third-order intermodulation intercept point (IIP3) is a large value at Δ f = f o, so the inline RF MEMS power sensor for Δ f > f o will not generate significant intermodulation distortion.

RF on-chip LC passive bandpass filter based on GaAs MMIC technology

The design and fabrication of a novel RF on-chip LC passive bandpass filter at S-band (2–4 GHz) based on using an LC passive lowpass filter and two DC-blocking capacitors are presented. The filter is accomplished with GaAs MMIC technology. Measurement results show that the quality factor (Q) of a 3 nH planar spiral MMIC inductor is 13.8 at 6.8 GHz and the self-resonant frequency is 15.5 GHz. The measured centre frequency of the bandpass filter shows agreement with the design performance and the contrast is 3.3%, the insertion loss of the filter is 6.7 dB at the centre frequency, and Q is 6.5.