GaAs Monolithic Microwave Integrated Circuit Research Articles

Gallium arsenide octave-bandwidth microwave voltage-controlled oscillator having discrete varicap

Modern reconfigurable communication systems demand microwave voltage-controlled oscillators (VCOs) possessing an octave-wide bandwidth. Many advanced applications require also a low phase noise and a low current consumption for such VCOs. To meet an octave-bandwidth specification in combination with a low phase noise and a low current consumption it is desirable to implement a microwave monolithic integrated circuit (MMIC) technology. In-house gallium arsenide (GaAs) MMIC technology is implemented to build VCOs in this work. At the same time, in order to achieve a high-Q wide frequency tuning range, we implemented also a discrete variable capacitance diode (varicap). The discrete varicap is stacked above MMIC oscillator chip. A vertical design structure of the discrete varicap guarantees a high overlap capacitance ratio (K>20) along with reduced affect of the parasitic reactance. A high overlap capacitance ratio is needed for an octave-wide frequency tuning, while reduced affect of the parasitic reactance increases Q-factor of the VCO resonator. Hence, a sequential integration of the discrete varicap over monolithic oscillator chip resolves referred tough challenges in the design of VCO. Integrated VCO is finally packaged as a surface-mount device (SMD). At that SMD ceramic package is sealed with the metal lid. The oscillator circuitry is based on the conventional negative resistance approach with a positive feedback realized by common-source capacitance. An active element of the oscillator is a pseudomorphic high electron-mobility transistor (pHEMT). The gate length of a transistor is 0.15 µm. The width of the gate varies from 240 µm to 360 µm depending on working frequencies of the VCO. The varicap is built on the GaAs epitaxial heterostructure having customized gradient doping profile with abrupt junction. Nonlinear behavioral model of the varicap is extracted from the diode measurements and is further used for VCO simulation. Two types of VCO have been designed, fabricated and tested. First (second) type of VCO provides a tuning range from 5 to 10 GHz (from 10 GHz to 20 GHz), respectively. The measurement results demonstrate an output power of 3.9 dBm; a current consumption of 30 mA at a supply voltage of 5 V; a phase noise of minus 90 dBc/Hz at 100 kHz offset (minus 85 dBc/Hz at 100 kHz offset) for the first (second) type of VCO, respectively.

Fabrication of a Novel GaAs Thermopile Sensor for RF Amplitude Demodulation

In this letter, a novel fabrication of straight-channel RF AM demodulator based on thermopile is presented. Its structure consists mainly of CPW line fed with AM signal, resistors and thermopiles to detect the demodulated signal. The structure is fabricated using GaAs Microwave Monolithic Integrated Circuit (MMIC) technology. Experiments are implemented and the results show that this thermopile-based demodulator is able to perform demodulation of AM signal with carrier frequency of 0.01-10 GHz and signal frequency of under 5 kHz. The influence of thermopile length on the performance is also studied and the result shows that when the thermopile length gets larger, the output amplitude of the demodulated signal gets larger, but its bandwidth gets smaller. In our scenario, the length of the thermopile can be set as 50 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula> m as a tradeoff between amplitude and bandwidth. 2022-0187

A 170–230 GHz High-Power Frequency Doubler Based on a GaAs MMIC Process

This letter reports a high-performance frequency doubler operating at 170–230 GHz based on a GaAs monolithic microwave integrated circuit (MMIC) process. The frequency doubler was designed with a balanced structure and the MMIC was inserted between two <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> -plane split-waveguide blocks. A “Pass-by” shaped biased filter was employed to improve the operation bandwidth. Measurement results showed that the doubler delivers continuous wave (CW) output power of 42–78 mW from 170 to 220 GHz with an efficiency of 14%–26%. With the increase of bias voltage, higher output power at higher frequency can be achieved, delivering a CW output power of 54–107 mW from 192 to 226 GHz at an efficiency of 18%–36%. At a very high input power level (600 mW), a maximum CW output power of 165 mW at 215 GHz with an efficiency of 27.5% has been demonstrated.

X-Band MMIC-Based Tunable Quasi-Absorptive Bandstop Filter

This letter reports on the design and experimental testing of a new class of tunable monolithic microwave integrated circuit (MMIC)-based quasi-absorptive bandstop filters (ABSFs). An asynchronous tuning method is used to improve the design robustness and obtain an ultrahigh stopband attenuation over a wide tuning range. RF tuning is facilitated by GaAs pHEMT varactors. The proposed filter configuration exhibits the following unique features: 1) ultrahigh stopband rejection (> 70 dB) despite using low quality factor lumped element (LE) resonators; 2) miniaturized footprint enabled by the GaAs MMIC process and the use of LE-based impedance inverter elements; and 3) frequency agility. An <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$X$ </tex-math></inline-formula> -band filter prototype was manufactured using a commercially available GaAs process. It exhibits a high isolation notch whose center frequency can be tuned between 8.7 and 10.5 GHz while having > 40-dB attenuation and a maximum attenuation of 73.6 dB.

An Ultrawideband GaAs MMIC Microstrip Directional Coupler With High Directivity and Very Flat Coupling

By introducing an adaptive lumped bridged-T amplitude equalizer into the microstrip directional coupler, this article realizes a 2.2 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times1.3$ </tex-math></inline-formula> mm ultrawideband GaAs monolithic microwave integrated circuit (MMIC) directional coupler with high directivity and very flat coupling by using the GaAs integrated passive device (IPD) process. The experimental results show that the proposed directional coupler exhibits more comprehensive radio frequency (RF) performance than the reported directional couplers due to the use of an adaptive bridged-T amplitude equalizer. In the ultrawide working frequency range from 2 to 20 GHz, the insertion loss of the coupler is less than 1.5 dB, the return loss is better than −20 dB, the coupling flatness is within ±0.3 dB, the isolation is higher than 40 dB, and the directivity is more than 20 dB, which are basically consistent with theoretical predictions. The microstrip directional coupler using the adaptive bridged-T amplitude equalizer shows great potential in the high-performance broadband communication system.

X-Band Quasi-Reflectionless MMIC Bandpass Filters With Minimum Number of Components

This article reports on the RF design and implementation of monolithic microwave integrated circuit (MMIC) bandpass filters (BPFs) with broadband symmetric quasi-reflectionless characteristics. They are based on in-series cascaded quasi-reflectionless stages that comprise one bandpass (BP) and two resistively terminated bandstop (BS) sections with approximately complementary transfer functions. This allows the resistors to absorb the reflected RF signal energy, and a quasi-reflectionless behavior is obtained at both the input and output ports of the BPF. The frequency selectivity of the BPF can be increased by: 1) introducing out-of-band transmission zeros (TZs) through inductive, capacitive, or resonant source-to-load couplings and/or by 2) increasing the number of stages in the overall filter. An on-chip integration scheme with minimum number of components is proposed using the commercially available PIH-110 GaAs MMIC process from WIN Semiconductors. Three prototypes were designed, manufactured, and measured at X-band. They demonstrated ultra-compact physical size and ultrawide >9:1 quasi-reflectionless characteristics.

A C-Band MEMS Frequency Discriminator With High Sensitivity and Linearity

This letter reports a C-band MEMS frequency discriminator with high sensitivity and linearity. The structure of the proposed discriminator is fabricated using GaAs Microwave Monolithic Integrated Circuit (MMIC) technology. The frequency discriminator consists of one dual-band power divider, one dual-band power combiner, one delay-line and the final MEMS thermoelectric power sensor. The purpose of the designed structure is to provide an ultra-wide working frequency band and simultaneously improve sensitivity and linearity. Both on-chip detector and packaged one are tested. S-parameter measurement illustrates good impedance matching covering 4–8 GHz. The frequency sensitivities of on-chip detector are $0.52~\mu \text{V}$ /MHz @ 17 dBm, $0.85~\mu \text{V}$ /MHz @ 20 dBm and $1.66~\mu \text{V}$ /MHz @ 23 dBm, while sensitivities of the packaged one are $0.43~\mu \text{V}$ /MHz @ 17 dBm, $0.84~\mu $ V/MHz @ 20 dBm and $1.48~\mu \text{V}$ /MHz @ 23 dBm, respectively. The experiment of response time shows that the rise time and fall time of on-chip detector are about $670~\mu \text{s}$ and $550~\mu \text{s}$ , while the corresponding times of the packaged one are about $980~\mu \text{s}$ and $730~\mu \text{s}$ .

C-Band Frequency-Tunable Rectifier Designed by HySIC Concept Utilizing GaAs MMIC and Si RFIC

In this letter, a frequency-tunable rectifier in the $C$ -band designed by a hybrid semiconductor integrated circuit (HySIC) concept is proposed. A GaAs monolithic microwave integrated circuit (MMIC) and a Si radio frequency integrated circuit (RFIC) were utilized as the HySIC configuration in the rectifier design. For the purpose of initial confirmation of this design validity, the GaAs and Si chips were fabricated and packaged onto the copper tungsten plate with gold plating. As measured results, frequency-tunable range from 3.82 to 4.55 GHz was measured. Maximum radio frequency (RF)–direct current (dc) conversion efficiency and output dc power in the measured power range from −10.0 to 17.8 dBm were 28.7% and 17.3 mW, respectively.

Microstructure Characterization and Interfacial Reactions between Au-Sn Solder and Different Back Metallization Systems of GaAs MMICs.

GaAs monolithic microwave integrated circuits (MMICs) with different back metallization systems (TiW/Au and Au/Ti/Au) exhibit different problems in the automatic Au-Sn eutectic bonding process, such as edge breakage or excessive voids. In this study, the formation mechanism of the edge breakage and excessive voids were investigated to prevent the damage of the MMICs in mass production scenarios. The microstructure and elemental distribution were studied using a scanning electron microscope and energy-dispersive spectroscopy. The void contents of the brazed region were measured with three-dimensional computed tomography. The top Au layer of the TiW/Au metallization partially dissolved in the melting An-Sn solder. Consequently, liquidus temperature of the solder increased, leading to isothermal solidification with the formation of ζ-Au5Sn in the scrubbing process, which was the reason for the edge breakage. The terminal Au film of the Au/Ti/Au metallization completely dissolved in the melting An-Sn solder. The metallurgical combination was achieved by the formation of the TiAu4 intermetallic compound between the Au-Sn solder and the Ti layer. The wettability of Au-Sn solder on Ti layer should be improved to prevent the formation of the excessive voids.

A $Ka$ -Band GaAs MMIC Traveling-Wave Switch With Absorptive Characteristic

A 36–38-GHz monolithic microwave integrated circuit (MMIC) single-pole double-throw (SPDT) switch employing a traveling-wave concept with absorptive characteristic is presented. The switch uses absorptive sections for better impedance matching in all ports. The switch obtained good linearity with the insertion loss of 3.2 dB, more than 28-dB isolation, and the return losses at all the ports are larger than 8.1 dB within the bandwidth of interest (36–38 GHz). The switch was fabricated by using GaAs 0.15- $\mu \text{m}$ process. The chip area is very compact, just about 1 mm $\times \,\, 1.1$ mm, including all the pads. To our best knowledge, this is the first GaAs MMIC traveling-wave switch type that has the absorptive characteristic.

Bent cantilever radio frequency microelectromechanical system power detector with improved linearity up to 1 W

This study reports a bent cantilever radio frequency microelectromechanical system power detector with improved linearity up to 1 W. The proposed device employs an upward bent cantilever for power detection. The novelty of this structure is that the bend of this kind in cantilever can realize the compensation for non-linear saturation at high power level effectively. As a result, the linearity will be improved on the condition of high power detection. An equivalent circuit model of mechanical principle is established to analyse the bent cantilever behaviour. The whole device is fabricated using GaAs microwave monolithic integrated circuit technology. The bent cantilever is constructed to overcome the stress gradient during deep etching releasing process. Measurement results prove the improved linearity from 100 mW to 1 W and the corresponding sensitivity is 2.8 aF/mW at 10 GHz.

A Micro-Machined Phase Discriminator With Improved Power Capacity on C-Band and X-Band

This paper reports a micro-machined phase discriminator with improved power capacity on C-band and X-band. The proposed phase discriminator is processed using GaAs microwave monolithic integrated circuit technology. First, a dual-frequency power combiner is designed to extend the working frequency band. Second, a sandwich-type thermoelectric power sensor is adopted to improve the power capacity. The unique device consequently has the advantages of ultra-wide band and high power capacity. The measurement results show good S-parameters within 6-12 GHz. The sensitivities among all measured frequency points are better than 42.3 μV/deg at 23 dBm, 82.5 μV/deg at 27 dBm, and 167.3 μV/deg at 30 dBm, respectively. What is more, the experiment of response time shows that the rise time is about 617.25 μs, while the fall time is about 304.69 μs.

Evolution of the Nonuniform Distributed Power Amplifier: A Distinguished Microwave Lecture

The emergence of gallium nitride (GaN) monolithic microwave integrated circuit (MMIC) technology has been a real game-changer for high-power amplifier and control components. When compared with the incumbent gallium arsenide (GaAs) MMIC technology, a near order of magnitude increase in output power and power handling was achieved with similar efficiency, noise, and frequency capability. In addition, GaN transistors epitaxially grow on high-thermal conductivity substrates such as silicon or silicon carbide (SiC), helping to mitigate some thermal issues associated with highoutput power density.

GaAs MMIC Low Noise Amplifier With Integrated High-Power Absorptive Receive Protection Switch

This letter reports a GaAs monolithic microwave integrated circuit (MMIC) low noise amplifier (LNA) with integrated high-power absorptive receive protection switch realized using 0.13- $\mu \text{m}$ GaAs pHEMT process. On-the-chip current distributed, resonant shunt FET switch configuration is employed for higher power handling. FET stacking technique is used to reduce the effective noise figure (NF). A two-stage LNA with integrated high power switch, forming each arm in a balanced configuration is employed to realize a monolithic LNA with integrated absorptive receive protection switch. This novel MMIC provides protection up to 20-W continuous wave and 2.9-dB NF, a gain of 20 dB over 9.3–9.9 GHz.

Liquid crystal polymer receiver modules for electron cyclotron emission imaging on the DIII-D tokamak.

A new generation of millimeter-wave heterodyne imaging receiver arrays has been developed and demonstrated on the DIII-D electron cyclotron emission imaging (ECEI) system. Improved circuit integration, improved noise performance, and enhanced shielding from out-of-band emission are made possible by using advanced liquid crystal polymer (LCP) substrates and monolithic microwave integrated circuit (MMIC) receiver chips. This array exhibits ∼15 dB additional gain and >30× reduction in noise temperature compared to previous generation ECEI arrays. Each LCP horn-waveguide module houses a 3 × 3 mm GaAs MMIC receiver chip, which consists of a low noise millimeter-wave preamplifier, balanced mixer, and IF amplifier together with a local oscillator multiplier chain driven at ∼12 GHz. A proof-of-principle partial LCP instrument with 5 poloidal channels was installed on DIII-D in 2017, with a full proof-of-principle system (20 poloidal × 8 radial channels) installed and commissioned in early 2018. The enhanced shielding of the LCP modules is seen to greatly reduce the sensitivity of ECEI signals to out-of-band microwave noise which has plagued previous ECEI studies on DIII-D. The LCP ECEI system is expected to be a valuable diagnostic tool for pedestal region measurements, focusing particularly on electron temperature evolution during edge localized mode bursting.

Enhancing performance of a InGaP/GaAs VCO by means of a switching architecture

The introduction of a compact switching architecture in the design of a monolithic microwave integrated voltage-controlled oscillator (VCO) is described, that is able to provide enhanced characteristics in term of both linearity and tunability. The proposed solution is applied to the design of a C-band GaAs MMIC (monolithic microwave integrated circuit) VCO. The chip has been realised with the heterojunction bipolar transistor (HBT) HB20M technology process provided by UMS Foundry. Measurements show a relative tuning range of about 30%, an average sensitivity of about 83 MHz/V, a minimum output power of 11.4 dBm and a phase noise at 100 kHz of frequency offset from the carrier lower of −107 dBc/Hz.

DC-25 GHz and Low-Loss MEMS Thermoelectric Power Sensors with Floating Thermal Slug and Reliable Back Cavity Based on GaAs MMIC Technology.

Wideband and low-loss microwave power measurements are becoming increasingly important for microwave communication and radar systems. To achieve such a power measurement, this paper presents the design and measurement of wideband DC-25 GHz and low-loss MEMS thermoelectric power sensors with a floating thermal slug and a reliable back cavity. In the sensors, the microwave power is converted to thermovoltages via heat. The collaborative design of the thermal slug and the back cavity, i.e., two thermal flow paths, is utilized to improve the efficiency of heat transfer and to ensure reliable applications. These sensors are required to operate up to 25 GHz. In order to achieve low microwave losses at the bandwidth, the floating thermal slug is designed instead of the grounded one. The effects of the floating slug on the reflection losses are analyzed by the simulation. The fabrication of these sensors is completed by GaAs monolithic microwave integrated circuits (MMIC) and micro-electro-mechanical systems (MEMS) technology. Measured reflection losses are less than −25.6 dB up to 12 GHz and −18.6 dB up to 25 GHz. The design of the floating thermal slug reduces the losses, which is equivalent to improving the sensitivity. At 10 and 25 GHz, experiments exhibit that the sensors result in sensitivities of about 51.13 and 35.28 μV/mW for the floating slug and 81.68 and 55.20 μV/mW for the floating slug and the cavity.

One to 40 GHz ultra‐wideband RF MEMS direct‐contact switch based on GaAs MMIC technique

This study presents a 1–40 GHz ultra-wideband radio frequency (RF) micro-electro-mechanical systems (MEMS) direct-contact switch based on a GaAs microwave monolithic integrated circuit (MMIC) process. The proposed switch utilises an inline cantilever membrane and a pull-in electrode to achieve ‘off’ and ‘on’ states. It has been manufactured by micro-machining, which is completely compatible with the GaAs MMIC process. An equivalent distributed parameter circuit model of the switch is established to analyse the microwave performances. The measured S-parameters show that the isolation (S21) in the ‘off’ state is better than 22.5 dB from 1 to 40 GHz. In the ‘on’ state, the input reflection coefficient (S11) is less than −20.9 dB and the forward transmission coefficient (S21) is better than −0.25 dB over the complete band. In addition, the measured pull-in voltage is ∼17.5 V. The measured maximum power handling capacity is 36.5 dBm. A lifetime of 2.4 × 107 switching cycles is also verified by this design. The whole structure is designed with the purpose of expanding its working bandwidth and achieving higher microwave performances over current state of art.

High Power, Thermally Efficient, X-band 3D T/R Module With Calibration Capability for Space Radar

Earth observation from space radar is based on the active electronically steerable antenna (AESA) whose performances count on reliable and powerful transmit/receive modules (TRM). To this aim, as a follow-up of the successful demonstration of a low-footprint transmit/receive hybrid module concept based on 3-D packaging and interconnect technologies (3DTRM), the interest for carrying out additional development work took a further step aiming at achieving a three-fold module performance improvement as well as at consolidating the novel proposed 3-D technology for space applications. First, the possibility of performing an AESA highly accurate calibration was implemented by embedding a wide band, high directivity directional coupler in the module circuitry without any total module footprint increase. Second, the heat extraction capability of the metal-ceramic hermetic package was enhanced through a re-design of the monolithic microwave integrated circuit (MMIC)-to-sink interface. And finally, the gallium arsenide (GaAs) MMIC high power amplifier (HPA) of the first 3DTRM version was replaced by a gallium nitride (GaN) HPA MMIC, obtaining both a higher transmit output power at 5 dB of compressed gain and an improved power added efficiency (PAE) at module level.

Improved Dynamic Range of Microwave Power Sensor by MEMS Cantilever Beam

This letter reports a microwave power sensor with improved dynamic range based on MEMS cantilever beam. The proposed power sensor is manufactured using GaAs microwave monolithic integrated circuit (MMIC) technology. In this design, a cantilever by-pass coupling structure is adopted for high power detection, while the terminating thermoelectric sensor is utilized for low power detection. The novelty of the proposed device is that the concatenation of a cantilever beam and the thermoelectric sensor allows the ultra-high dynamic range power detection. Measurement results show that the sensitivities are 0.0315, 0.0261, and 0.0237 mV/mW at 1, 2, and 3 GHz for input power from 0.1 to 100 mW, respectively. For input power from 100 mW to 1W, the sensitivities are 2.398, 3.753, and 5.416 μV/mW at 1, 2, and 3 GHz, respectively. This compact power sensor has the potential prospect for dynamic range application.