RF MEMS Thermistor Power Sensor Based on Wheatstone Full-Bridge Structure

Future communications satellites are likely to use gallium arsenide (GaAs) monolithic microwave integrated-circuit (MMIC) technology in most, if not all, communications payload subsystems. Multiple- scanning beam antenna systems are expected to use GaAs MMIC's to increase functional capability, to reduce volume, weight, and cost, and to greatly improve system reliability. RF and IF matrix switch technology based on GaAs MMIC's is also being developed for these reasons. MMIC technology, including gigabit-rate GaAs digital integrated circuits, offers substantial advantages in power consumption and weight over silicon technologies for high-throughput, on-board baseband processor systems. In this paper, current developments in GaAs MMIC technology are described,and the status and prospects of the technology are assessed.

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.

In this work, a short wavelength microstrip line employing periodically arrayed capacitive elements (PACE) on GaAs monolithic microwave integrated circuit (MMIC) was developed for application to miniaturized on-chip passive components. The microstrip line employing PACE showed a wavelength much shorter than conventional transmission line. Concretely, the wavelength of the microstrip line employing PACE was only 10 % of conventional microstrip line on GaAs MMIC. Using the microstrip line employing PACE, a highly miniaturized impedance transformer was fabricated on GaAs MMIC. The impedance transformer showed good RF performances in a broad band from S to X band. Concretely, the return and insertion loss are −28 and −1.4 dB, respectively, at a center frequency of 7 GHz, and return loss values better than −10 dB were observed from 3.2 to 9.2 GHz, and insertion loss values of −1.5 ± 0.5 dB were observed in the above frequency range. The size of the impedance transformer was 0.042 mm2, which is 0.95 % of the size of the conventional transformer on MMIC.

This paper presents a unique design concept for a dual-frequency,electronically steerable, MM-wave phased array antenna using Monolithic Microwave Integrated Circuit (MMIC) technology. Such an antenna design will be found most attractive for satellite communication and missile seeker applications, where size, weight and power consumption are the most stringent requirements. The block diagram of a dual-frequency (20 GHz/30 GHz), electronically steerable, phased array antenna using MMIC technology is shown in Figure 1. Specific details on the critical RF components are also shown in Figure 1. Because of the location of the radiating elements on the hemispherical surface, the antenna is inherently capable of providing electronic scanning over 360 deg. in AZ-plane and over plus/minus 60 deg. in EL-plane. This electronically steerable phased array antenna will generate multiple beams in the AZ-plane with consistent bandwidth and pattern symmetry. This design exploits true integration of printed circuit antenna technology, GaAs active device technology, MM-wave microstrip technology and printed circuit time delay phase shifting element technology. This design employs microstrip periodic structure transmission line sections as time delay phasing elements, which requires no input power. The printed circuit microstrip line sections will be used as feed networks. Two distinct dual- frequency, antenna element fabrication techniques, namely, stacked-patch element (Figure 2a) and collocated, interleaved-patch element (Figure 2b), were investigated in terms of cost, size, performance and complexity. Tradeoff studies performed seem to indicate that stacked-patch element approach will offer minimum size and weight. The physical dimensions shown in Figure 1 and 2 are computed for 20 GHz and 30 GHz operations. All the electronics, control circuits and RF MMIC circuits can be located within the hemispherical structure. The input power, overall system size and weight will depend on the antenna gain requirement, inter-element spacing, number of elements and phase shifter types. It is important to mention that delay line phasing networks using printed circuit periodic structures will provide optimum flexibility in phasing of the antenna elements with minimum loss. The proposed antenna architecture for a dual-frequency operation using a common aperture and MMIC technology seems to offer an antenna system with minimum cost, size, weight and power consumption.

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.

Rapid expansion of microwave systems in phased array radar and commercial applications in the emerging wireless communication system areas requires affordable, compact, lightweight, reliable, solid state, integrated microwave transmit/receive (T/R) modules. Traditional microwave modules fabricated using microstrip-based hybrid/ monolithic integrated circuitry are incompatible with low cost, high volume, robotics manufacturing techniques for multi-chip microwave modules, because of the fragile nature of current 4 mil-thick gallium arsenide monolithic microwave integrated circuits (MMICs). Backside processing, including wafer thinning and via-hole ground electrode access, are also significant yield limiting factors for MMIC manufacturing. Hughes has developed a novel, robust, flip-chip approach for microwave T/R modules using self-aligned, solder reflow, multichip assembly techniques. The rugged (25 mil thick), passivated MMIC chips with coplanar waveguide circuitry, silicon-like, on-chip multilayer metal interconnects, with off-chip plated metal electrical/thermal paths offers major advantages over conventional MMICs (Table 1). Elimination of wafer thinning will be critical for processing and handling of large-diameter wafers. The use of plated metal thermal bumps directly on top of active circuit elements leads to 30% thermal property improvement over conventional GaAs MMICs.

[Abstract] Regressive equations that calculate the maximum channel temperature of a GaAs monolithic microwave integrated circuit (MMIC) have been made through a lot of finite element (FE) analyses. And this paper suggests how to estimate the maximum channel temperature with those regressive equations for frequent cases. As an example, a medium power amplifier’s maximum channel temperature was calculated and its result was larger than that of a complete FE model by about 4%. The medium power amplifier’s temperature distribution was obtained through an infrared scan and, even though the maximum channel temperature could not be obtained due to the test’s inherent shortcoming, temperature other than gate fingers showed good agreement with FE analysis results. Therefore it can be said that the practical method for obtaining the maximum channel temperature using regressive equations can give thermal resistance of a GaAs MMIC very easily and quickly without time-consuming FE analyses.

GaAs microwave monolithic integrated circuits (MMICs) with Ba1−XSrXTiO3 (BST) capacitors have been developed. Spin-coating of sol-gel solution was used to make the BST thin film. The obtained BST film has a dielectric constant of 300 that is 50 times higher than the conventional SiN one. The capacitance has the frequency roll-off over 2 GHz, which is sufficient enough for a variety of consumer applications. The implemented GaAs MMICs with on-chip BST capacitors enable the positive-bias supply and high gain performance as well as the small package outline.

A method for first-pass MMIC (monolithic microwave integrated circuit) design success is presented. The power of statistical design and modeling is combined with that of circuit-level electromagnetic simulation in a CAD (computer-aided-design) system, providing the ultimate means for predicting production success. The performance of the proposed CAD system is verified by comparing simulated and actual statistical response characteristics of a three-stage, 7-11-GHz low-noise-amplifier GaAs MMIC.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Recent progress of GaAs Monolithic Microwave Integrated Circuit (MMIC) and Gb/s logic has established a solid foundation for many future system applications. Systems benefiting from these advances include phased/adaptive arrays, MILSATCOM, Television Receive-Only (TVRO) receiver, Electronic Warfare (EW), instrumentation and radar. This paper presents various MMIC technologies and tradeoffs of materials (crystal growths, orientations, material properties, characterization techniques, etc.), processes (ion-implantation, Molecular Beam Epitaxy, Vapor Phase Epitaxy, Liquid Phase Epitaxy), and circuit fabrication via hole, air bridge, active matching, etc. The performance of the presently achieved SHF/EHF MMIC's are summarized. Technical problems, possible solutions, and future trends of MMIC design and fabrication (impedance matching methods, bias, low noise techniques, medium power IC's, EHF circuits, filters, isolators, packaging techniques, etc.) are also described.

This paper proposes an inline insertion microwave microelectromechanical systems (MEMS) power sensor based on measuring the power dissipated by intrinsic ohmic losses of a coplanar waveguide (CPW) signal line by thermopiles. In order to achieve ultra reflection losses, cold junctions of the thermopiles are covered with the CPW ground lines for depressing electromagnetic coupling effects and serving as hot sink. To increase the sensitivity, the CPW ground lines are suspended above hot junctions of the thermopiles for reducing thermal losses and the CPW dimension near the thermopiles is designed to increase the temperature of the hot junctions. This sensor is completely compatible with the GaAs monolithic microwave integrated circuits (MMIC) technology. Experiments show that this optimized power sensor has resulted in reflection losses of less than -24.3 dB up to 26 GHz, with insertion losses of less than 0.37 dB. For the input power of 0.5-300 mW, the good linearity of the output response is obtained and average sensitivities are more than 6.26 and 8.21 mV/W at 2 and 20 GHz, respectively.

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.

A design of 18 - 20 GHz GaAs Monolithic Microwave Integrated Circuit (MMIC) 4-bit phase shifter is presented. The phase shifter adopts high-pass/low-pass type and switched filter networks. The passive HEMTs are used as key components for controlling the phase shift. All the drain and source terminals are DC grounded while the gates are applied with 0 V or −3 V. The power consumption is almost zero. The phase shifter obtains 9 ± 1 dB insertion loss and the input and output return losses are higher than 9.8 dB over the 18 - 20 GHz bandwidth of interest. The phase resolution is 22.5° with the root mean square (RMS) phase error is less than 5° within the bandwidth. The phase shifter is designed by using GaAs 0.15 µm process. The chip area is very compact, just about 2 mm ×1 mm, including all the pads.

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

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.