MMICs insertion in a Ku-band active phased array for communications satellites

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.

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.

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.

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.

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.

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.

This paper presents the design and measured results of a high-performance, miniature 6-/4-GHz receiver for on-board satellite applications. The receiver has a gain of 76 dB, weighs less than 500 g, and consumes less than 5 W of DC power. Extensive use is made of custom-designed monolithic microwave integrated circuit (MMIC) chips for all RF functions, to achieve a high level of reliability and miniaturization. A pseudomorphic high-electron-mobility transistor (p-HEMT) C-band low-noise amplifier with 40-dB gain and a room temperature minimum noise figure of approximately 0.85 dB is used in the front end. Gain adjustments are provided in l-dB steps at IF frequency between 3.5 and 4.5 GHz.

Design of Digital Phase Shifters for Multipurpose Communication Systems aims to cover a new emerging need in designing digital phase shifters for modern communication systems. With the advancement of new generation mobile communication systems, directed beams save a substantial amount of RF-power, and improve the noise immunity. In this regard, beam-forming circuits, namely, digital phase shifters constitute essential parts the antenna arrays. Therefore, this book is devoted to design of digital phase shifters for various communications systems.In the good old days, phase shifter design requirements used to demand narrow bandwidth with no physical size constraints. Nowadays, they must be compact and suitable for Very Large Scale Integrated Circuits (VLSI) or Microwave Monolithic Integrated Circuit (MMIC) implementation with Wide Phase Range (WPR) and Wide Frequency Band (WFB).Since the 1980s, the author has been designing digital phase shifters for various applications. He started to work with loaded lines phase shifters, and then employed branch line couplers to achieve wider frequency bands. In order to reduce the physical size, he used a 3 element Symmetric LC ladder based T or PI configurations. In order to achieve broad frequency band with large phase range, usage of LC lattice structures is inevitable. Lately, the author designed phase shifters using both lowpass and highpass LC ladder and lattice based switched-structures, which are suitable for monolithic implementation. In the course of design, MOS transistors were employed as switching elements. This book includes several novel digital phase shifter topologies, which provides wide phase range and wideband operation.Technical topics discussed in the book include:- Basic Concept of Antenna Arrays- Concept of Digital Phase Bit- Scattering Parameters to analyze the electric performance of phase shifters- Transmission Lines as circuit elements to construct practical phase shifters- Loaded Line Digital Phase Shifters (DPS)- Lowpass Based T/PI Section DPS- Highpass Based T/PI Section DPS- 3-Element LC T/PI Section DPS- Wide Phase Range, Wide Frequency Band Symmetric Lattice Based DPSFor each topology presented, explicit design equations are provided and programs to assess the electric performance of each topology is developed in a MatLab environment. It is expected that the reader will be self-sufficient to design and implement the digital phase shifters topologies presented in this book.

Design of Digital Phase Shifters for Multipurpose Communication Systems aims to cover a new emerging need in designing digital phase shifters for modern communication systems. With the advancement of new generation mobile communication systems, directed beams save a substantial amount of RF-power, and improve the noise immunity. In this regard, beam-forming circuits, namely, digital phase shifters constitute essential parts the antenna arrays. Therefore, this book is devoted to design of digital phase shifters for various communications systems. In the good old days, phase shifter design requirements used to demand narrow bandwidth with no physical size constraints. Nowadays, they must be compact and suitable for Very Large Scale Integrated Circuits (VLSI) or Microwave Monolithic Integrated Circuit (MMIC) implementation with Wide Phase Range (WPR) and Wide Frequency Band (WFB). Since the 1980s, the author has been designing digital phase shifters for various applications. He started to work with loaded lines phase shifters, and then employed branch line couplers to achieve wider frequency bands. In order to reduce the physical size, he used a 3 element Symmetric LC ladder based T or PI configurations. In order to achieve broad frequency band with large phase range, usage of LC lattice structures is inevitable. Lately, the author designed phase shifters using both lowpass and highpass LC ladder and lattice based switched-structures, which are suitable for monolithic implementation. In the course of design, MOS transistors were employed as switching elements. This book includes several novel digital phase shifter topologies, which provides wide phase range and wideband operation. Technical topics discussed in the book include: • Basic Concept of Antenna Arrays • Concept of Digital Phase Bit • Scattering Parameters to analyze the electric performance of phase shifters • Transmission Lines as circuit elements to construct practical phase shifters • Loaded Line Digital Phase Shifters (DPS) • 180° - Lowpass Based T/PI Section DPS • 180° - Highpass Based T/PI Section DPS • 180° 3-Element LC T/PI Section DPS • 180° Wide Phase Range, Wide Frequency Band Symmetric Lattice Based DPS For each topology presented, explicit design equations are provided and programs to assess the electric performance of each topology is developed in a MatLab environment. It is expected that the reader will be self-sufficient to design and implement the digital phase shifters topologies presented in this book.

메타 물질의 한 형태인 LHTL(Left-Handed Transmission Line)과 기존의 전송 선로 형태인 RHTL(Right-Handed Transmission Line)을 이용하여 광대역 I-Q 벡터 신호 생성을 위한 <TEX>$90^{\circ}$</TEX> 커플러를 설계, 제작하고 측정을 하였다. LHTL과 RHTL 모두 커패시터와 인덕터를 이용하여 합성 전송 선로 형태로 구성함으로써, 그 크기를 최소화 하였다. 또한, 제안된 커플러 제작에 필요한 Wilkinson 전력 분배기를 합성 RHTL을 이용하여 간단하게 구현함으로써 전체 회로의 크기를 <TEX>$11mm{\times}12mm$</TEX>로 만들 수 있었다. 주파수 범위 0.8~1.25 GHz에 대해 출력의 위상 차이가 <TEX>$90^{\circ}{\pm}5^{\circ}$</TEX>를 유지함으로써 광대역 <TEX>$90^{\circ}$</TEX> 커플러를 작은 크기로 만들 수 있었다. 동 주파수 범위에 대해 삽입 손실을 1.6 dB 이하로, 반사 손실을 10.1 dB 이상으로 유지 가능했다. 필자가 아는 한 이는 그 주파수 대에서 가장 작은 광대역 <TEX>$90^{\circ}$</TEX> 커플러이며, MMIC(Monolithic Microwave Integrated Circuit)로 만들 경우 그 크기를 훨씬 더 줄일 수 있을 것이다. By using LHTL(Left-Handed Transmission Line) which is a form of a metamaterial and conventional RHTL (Right-Handed Transmission Line), we designed, fabricated and tested a broadband <TEX>$90^{\circ}$</TEX> coupler which is a basic circuit for I-Q vector signal generation. Synthetic LHTL and RHTL were implemented with capacitors and inductors only, that the size is minimized. Also, by implementing a Wilkinson power divider which is required for the suggested circuit using a synthetic RHTL, the size of whole circuit is only <TEX>$11mm{\times}12mm$</TEX>. For the frequency range 0.8~1.25 GHz, the phase difference at the outputs maintained <TEX>$90^{\circ}{\pm}5^{\circ}$</TEX> and thus, a broadband <TEX>$90^{\circ}$</TEX> coupler could be made in a compact form. for the same frequency range, the insertion loss is less than 1.6 dB and return loss is more than 10.1 dB. To the best of our knowledge, this is the smallest and broadband <TEX>$90^{\circ}$</TEX> coupler for the frequency range and if the circuit is made with MMIC(Monolithic Microwave Integrated Circuit) technology, the size will be reduced much further.

In this paper, we have first proposed a RF MEMS thermistor power sensor based on Wheatstone full-bridge structure. The proposed RF MEMS thermistor power sensor is fabricated using GaAs MMIC (monolithic microwave integrated circuit) technology. In this device, two parallel low TCR (temperature coefficient of resistance) heaters are employed to keep the impedance match stable. And a Wheatstone full-bridge formed by four identical thermistors is used for the unknown RF power measurement. To improve the sensitivity of the sensor, a MEMS substrate membrane is fabricated beneath the hot area to suppress longitudinal heat loss by back etching process. The whole structure is integrated with CPW transmission line, which has the potential of high integration density. Compared with traditional thermistor power sensor, this device has both advantages of stable impedance match and high sensitivity.

A thin-film microwave limiter has been developed through a joint partnership between researchers in China and America. This limiter is fabricated using thin-film hybrid integrated circuit technology (TFHICT) on a ceramic substrate with high relative permittivity. The result is a compact circuit, with no PbSn welding points, ensuring high reliability. The thin film microwave limiter is far more compact than can be achieved with thick film technology, as this size comparison shows Limiters are used to protect weak components, such as low noise amplifiers, from stray signals. The power transfer characteristic behaves somewhat like an amplifier with low loss rather than gain. Above critical input power, the output can behave quite strangely, often being described as having a “kink” in it. This circuit technology brings with it the advantage of miniaturisation without compromising reliability. This allows it to be deployed in areas where there are volume restrictions, such as satellite applications. Where traditional thick-film technology employs a chemical solvent etching procedure, metal thin-films use vacuum deposition technology to ensure higher processing precision. This precision is achieved by directly integrating some passive circuits, thin-film resistors, and planar spiral inductors into the substrate itself. Other alternatives, such as advanced monolithic microwave integratedcircuit (MMIC) and low temperature co-fired ceramic (LTCC) technology, require greater expenditure and take far longer to manufacture. Metal thin-films, therefore, are cheaper, more precise, can be produced more quickly, and offer greater flexibility for the engineers. With the rapid development of thin-film hybrid integrated circuit technology, the resulting microwave limiters that can be assembled have become a key component in the front-end of receivers because of its compact size, excellent performance and high reliability. The balanced limiter circuit configuration could be easily expanded to perform a variety of functions, such as radar duplexers, and multi-function circuits used as balanced limiter low-noise amplifiers. It is practical to produce these passive duplexers as they use a common antenna for transmitting and receiving. The balanced microwave limiter could isolate the receiver from the transmitter when producing high-power transmissions, using the microwave conductivity modulation effect of the PIN diodes. Looking further ahead, the team anticipate that metal TFHICT could be utilised in three-dimensional, multi-functional circuits suitable for millimetre wave and terahertz frequencies. This would satisfy the more stringent requirements for the next generation of radar, satellite communication, and of other wireless fields. This work is actually already part of real world engineering, and it is a crucial circuit in the front-end radar receiver systems. The fabricated thin film balanced low noise amplifier with the limiter embedded

This paper has two objectives: to discuss the role of small satellites in the satellite communications R&D (research and development) in the IT (Information Technology) era, and to show communications technology topics in small satellite applications. The need for small satellite communications is first discussed. The future (next three decades) vision of satellite communications R&D is then described, corresponding to the recent rapid increase of capacity of terrestrial links. Third, the role of small satellites in future satellite communications R&D is discussed. Finally, small satellite related communications technology topics are described to show that there are many interesting research issues.

The basic principles of building a promising domestic regional satellite communication system "Express-RV", based on the highly elliptical orbit "Molniya" and intended for broadband access of civil sector subscribers to various public communication networks, in particular to the Internet, are considered. The main technical requirements for the antenna systems of mobile satellite communication terminals of the Express-RV system are formulated. The necessity of using active phased array antennas for a number of types of such terminals is justified. A brief overview of the principles of implementation and examples of the design of microstrip active phased array antennas, including their elementary emitters and individual modules, are given. The problem of the occurrence of the blinding effect inherent in flat microstrip gratings made on dielectric substrates is noted; measures to compensate for this effect are considered. The possibility of expanding the maximum scanning angle of a narrowly directed beam of an active phased array antenna by using a magnetically controlled scattering dielectric lens, as well as creating segment-dome structures of antenna systems in relation to mobile terminals of mobile satellite communications of the "Express-RV" system, is shown. Simple analytical relations are derived that allow us to estimate the number of elementary emitters required for the implementation of a receiving-transmitting active phased array antenna with specified technical characteristics: gain and maximum scanning angle; the corresponding dependencies are given. The cost of creating an antenna system based on an active phased array is estimated.

This paper discusses NASA Lewis Research Center's program for development of monolithic microwave integrated circuits (MMIC) for application in space communications. Emphasis will be on the improved performance in power amplifiers and low noise receivers which has been made possible by the development of new semiconductor materials and devices. Possible applications of high temperature superconductivity for space communications will also be presented.