Military applications for heterostructure microelectronics technology

In this paper, we present simple digital-based pulse generators (PGs) that emit short pulses with a full width at half-maximum (FWHM) of only several picoseconds in order to realize millimeter-wave impulse radio (IR) systems that can transmit signals at 10 Gbps and above. There are distinctive advantages of using digital techniques. Scaling devices and reducing parasitic capacitances can enhance performance, which is examined by a transition analysis of the PGs. Secondly, retiming techniques enable the PGs to suppress jitter, which is essential for maintaining transmission quality. Two types of PGs are demonstrated: Type-I PG with advanced 75 nm InP-based high electron mobility transistors (HEMTs) having a cavity structure generated short pulses with a record FWHM of <4.9 ps at 20 Gbps, realizing sub-THz IR systems. Type-II PG with mature 100 nm InP-based HEMTs without the cavity retimed 6.5 ps pulses, resulting in very small jitter of 256 fs. Type-II PG was used to construct an IR transmitter of over 10 Gbps at millimeter-wave frequencies (75–110 GHz).

Metal-organic vapor-phase epitaxy (MOVPE) growth of InP was investigated by using both triethylphosphine (TEP) and phosphine (PH/sub 3/) simultaneously as phosphorus sources. Excellent surface morphology was obtained at 630 and 660/spl deg/C by using both TEP and phosphine simultaneously at an optimized balance even though the phosphine supply amount was drastically reduced. The regular monolayer-step array of the sample surface indicates the enhancement of step-flow growth attributed to the enhancement of phosphorus source supply. By using this method, we obtained the InP recess-etching stopper layers of InP-based high electron mobility transistors (HEMTs) with excellent etching selectivity. Low-temperature InP growth at 475/spl deg/C and below was also examined for the growth of emitter in InP-based heterojunction bipolar transistors (HBTs). It is confirmed that this growth method is quite effective for the improvement of InP crystal quality of InP-based epiwafers and the cost reduction for epiwafer production.

Microwave signals carry important intelligence information in electronic warfare. Hence, the measurement of microwave signals plays a very important role. Traditional electronic microwave measurement systems are not appropriate for the instantaneous frequency measurement (IFM) of high-speed signals. A simple and low-cost photonic approach to the IFM based on frequency-to-power mapping is proposed and demonstrated with a reasonable resolution. The measurement is performed on account of a double Mach–Zehnder modulator (MZM), single-mode fiber (SMF), photodetector (PD), and signal processing. The scheme using four wavelengths achieves resolutions of ±0.1 and ±0.09 GHz respectively for the 15.8–18.4 and 18.4−21.2 GHz frequency measurement ranges. Therefore, the scheme is a broad prospects method for high-resolution IFM. Moreover, it is of great importance for applications in electronic warfare and high-resolution sensor systems.

We present self-consistent Monte Carlo simulations of the collectors of Si and GaAs heterojunction bipolar transistors (HBTs) with wide (700 nm) collectors such as are used in power transistors. Recent experimental data on peak cut-off frequencies of 76 GHz for GaAs/AlGaAs HBTs have provided strong direct evidence for extended velocity overshoot in the collector under base push-out conditions and there are theoretical results using fast semi-analytic techniques confirming this explanation. Our aim is to investigate how these regions of extended velocity overshoot might form and how they would affect at high current densities in such structures. Differences in velocity - field characteristics and velocity overshoot between Si and GaAs collectors have large effects which are quantified by calculating . Comparisons are also made with data from the semi-analytic results.

Design and test results are presented for several multiuse GaAs ICs for radar and electronic warfare (EW) applications. The chips described are a redundant switch, a broadband distributed amplifier, a broadband variable-gain amplifier, a 2.5-GHz sample and hold, a 1-GHz analog-to-digital converter, and an L-band buffered prescalar. These ICs, fabricated with the ITT 0.4- mu m-gate MESFET multifunction self-aligned gate (MSAG) process, demonstrate excellent performance.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Performance improvements of Si/GexSi1-x/Si heterojunction bipolar transistors with linearly graded Ge profile in the epitaxial base layer are compared with Si transistors without Ge by using a combined DC and low-frequency (1 kHz) small-signal AC measurements. Quantitative analysis of the minority-carrier transport parameters in the GeSi base layer, and of the current gain and recombination current components, for both GeSi and Si transistors are reported for the first time. The two fold improvement of the base transit time in GeSi transistors is due to the built in electric field irom Ge grading, rather than to improved diffusivity.

An oscillator is a vital component as the energy source in microwave telecommunication system. Microwave oscillators designed using Gunn diode have poor DC to RF efficiency. IMPact Ionization Avalanche Transit-Time diode (IMPATT) oscillators have the drawback of poor noise performance. The transistorized oscillators have a limitation to the maximum oscillation frequency which means that they cannot be used for oscillators designed for high frequencies. To design negative series feedback Dielectric Resonator Oscillator (DRO), the resonant unit uses a dielectric resonator (DR) since it is small in size, light in weight, has high-Quality ([Formula: see text]) factor, better stability and also it is inexpensive. It has the benefits of low-phase noise, low cost, miniaturization, high stability, applicable for devices designed at high frequencies and had already been widely applied, so the research on microwave dielectric oscillator has also been one of the focus of today’s microwave integrated circuits. DRO is widely used in electronic warfare, missile, radar and communication systems. The DRO incorporates High-Electron Mobility Transistor (HEMT) as an active device since it offers higher power-added efficiency combined with excellent low-noise figures and performance. The entire circuit of DRO using HEMT at 26[Formula: see text]GHz is designed using Agilent Advanced Design System (ADS) software. In this, DRO different measurements of parameters are done such as output power which is typically [Formula: see text][Formula: see text]dBm for 26[Formula: see text]GHz DRO, phase noise at 10[Formula: see text]kHz offset for 26[Formula: see text]GHz DRO it is 80[Formula: see text]dBc/Hz. The frequency pushing and frequency pulling for 26[Formula: see text]GHz DRO its typical values are 30[Formula: see text]kHz/V and 1[Formula: see text]MHz, respectively.

The cross ambiguity function (CAF) has been commonly used to find time difference of arrival (TDOA) and frequency difference of arrival (FDOA). In most cases, direct computation of the CAF by using a conventional method such as fast Fourier transform is too computationally intensive. Thus, a two-stage approach consisting of a coarse mode to find rough TDOA/FDOA estimates and a fine mode for precise estimation was introduced. However, there has been no methodology for selecting an interpolation factor determined by the sampling frequency and target precision which significantly affects the computational complexity. In addition, even if the computational complexity can be reduced by using the optimal interpolation factor, the huge transmission data through the datalink between sensors and the central station still remains to be an obstacle for an electronic warfare (EW) system. In this respect, we derive an optimal interpolation factor and then propose a new two-stage TDOA/FDOA estimation algorithm using a resampling block to reduce the computational complexity and the data size simultaneously in EW systems. In the proposed method, the optimal interpolation factor can be used irrespective of the sampling frequency and the target precision. Simulation results show that the optimal interpolation factor efficiently reduces the computational burden without the loss of estimation performance.

The authors report on the state-of-the-art power performance of InP-based HEMTs (high electron mobility transistors) at 59 GHz. Using a 448- mu m-wide HEMT with a gate length of 0.15 mu m, an output power of 155 mW with a 4.9-dB gain and a power-added efficiency of 30.1% were obtained. By power-combining two of these HEMTs, an output power of 288 mW with 3.6-dB gain and a power-added efficiency of 20.4% were achieved. This is the highest output power reported with such a high efficiency for InP-based HEMTs, and is comparable to the best results reported for AlGaAs/InGaAs on GaAs pseudomorphic HEMTs at this frequency. >

Electronic warfare (EW) is an important capability that can advance desired military, diplomatic, and economic objectives or, conversely, impede undesired ones. In a military application, EW provides the means to counter, in all battle phases, hostile actions that involve the electromagnetic (EM) spectrum-from the beginning when enemy forces are mobilized for an attack, through to the final engagement. EW exploits the EM environment by sensing and analyzing an adversary's application of the spectrum and imposing appropriate countermeasures (CMs) to hostile spectrum use. EW sensors are one means by which the military gathers tactical intelligence from noncooperative forces. EW sensors, together with EW CMs, mitigate the effectiveness of an adversary's electrooptic/infrared, and radio frequency-controlled weapons. EW enhances the survivability of the host force through control and manipulation of the EM environment and denies or limits its use by an adversary. EM spectrum CMs to threat systems can be selectively applied on a time- and/or frequency-multiplexed basis so that host force use of the EM spectrum is uninhibited.

The HEMT (high electron mobility transistor) LSI perspective is presented, and technological challenges for VLSI are addressed, including the performance advantage in the deep-submicron range, device size and voltage scaled-down approaches, and self-aligned InGaAs-based HEMTs. In addition, the future directions of HEMT technology are projected, focusing on InGaAs-based device technology compared with GaAs-based HEMT LSI technology. >

Rapid progress in multimedia communication requires large capacity optical transmission lines over 10 Gbit/s. One of the candidates considered for forthcoming high speed transmission systems is 20 Gb/s optical IM-DD transmission system. There have been several reports about IM-DD optical transmission experiments at 20 Gbit/s (1, 2, 3, 4). Monolithic integrated circuits are indispensable to turn such high speed optical transmission systems into practical application. The performance of various monolithic ICs for optical communications is summarized in Fig. 1. Si ICs are very attractive for realizing the high speed IM-DD systems up to 20 Gbit/s, because of their high uniformity and yield (5, 6, 7). The Si bipolar transistors, however, are not suited to fabricate circuits with high output voltage swing such as modulator driver, because of their breakdown voltage limitation. The compound devices, such as GaAs-HBTs, GaAs-MESFET and heterojunction FETs, have high cut-off frequency over 100 GHz (8, 9), so they are very effective to achieve the high speed ICs operating over 20 Gbit/s. They also have the advantage of utilizing microwave circuit technologies, which make it possible to design high frequency narrowband circuit, such as a clock amplifier at over 20 GHz.

Characterization of single event effect simulation in InP-based High Electron Mobility Transistors

The performance damage mechanism of InP-based high electron mobility transistors (HEMTs) after proton irradiation has been investigated comprehensively through induced defects. The effects of the defect type, defect energy level with respect to conduction band ET, and defect concentration on the transfer and output characteristics of the device are discussed based on hydrodynamic model and Shockley–Read–Hall recombination model. The results indicate that only acceptor-like defects have a significant influence on device operation. Meanwhile, as defect energy level ET shifts away from conduction band, the drain current decreases gradually and finally reaches a saturation value with ET above 0.5 eV. This can be attributed to the fact that at sufficient deep level, acceptor-type defects could not be ionized any more. Additionally, the drain current and transconductance degrade more severely with larger acceptor concentration. These changes of the electrical characteristics with proton radiation could be accounted for by the electron density reduction in the channel region from induced acceptor-like defects.

AlGaN/GaN high electron mobility transistors (HEMTs) have potential applications in the next generation high-power microwave and switching devices. They can maintain robust device characteristics under high temperature operation and high voltage conditions because of their superior material properties [1]. Sapphire and SiC are popularly used as substrate materials for GaN optoelectronic devices. Recently GaN on Si (111) technology has found applications in electronic devices because of its low cost and superior scalability of wafer size. In this study, 0.5µm gate length GaN on Si HEMT technology was proposed and demonstrated with field-plate technology. This GaN on Si HEMT process realized the high performance microwave and power electronics and circuits successfully.