Showing papers on "IMPATT diode published in 2017"

Space Charge Effect of IMPATT Diode Using Si, Ge, GaAs, InP, WzGaN and 4H-SiC at Ka-Band

Abstract: Extra space charges are generated in the drift region due to the avalanche multiplication process and space charge effect of IMPATT (impact ionization and avalanche transit time) diode reduces the efficiency of the devices. The disturbances in electric field, drift voltage, and space charge resistance represent the space charge effect. In this paper, a comparative study of these disturbances has been presented for silicon, germanium, gallium arsenide, indium phosphide, WzGaN (wurtzite gallium nitride), 4H-SiC (silicon carbide) semiconductor materials-based double drift region (DDR) IMPATT diode at Ka-band as well as the cause of poor efficiency in the diode highlighted. This will be helpful for the selection of the suitable material for optimum design of DDR IMPATT diode as well as to improve the DC to radio frequency (RF) power conversion efficiency.

A new model of heterostructure GaAs/Ge IMPATT diode at W-band frequency

Abstract: In this paper, a new heterostructure based on GaAs/Ge impact ionization avalanche transit time diode (IMPATT) is investigated at 94 GHz design frequency, with an emphasis on the optimized current density A complete theoretical simulation with validatation of experimental results found that this type of structure is possible for high efficiency near about 135 % as compared to Ge (13 %) and GaAs (11 %) homostructure devices But the rf power in case of GaAs is higher of about 788 mW as compared to other diodes because of due to high breakdown voltage The result shows that heterostructure based IMPATT diode gives high efficiency with moderate power The available experimental methods and the simulation results will be suitable for high efficiency diode used for communication

Investigation of the design specifics of controlled microwave chaos generators based on the microwave diodes

Abstract: In this article, the results of experimental research of microwave chaotic oscillation generator based on the IMPATT diode are discussed. The methods to control of generated microwave chaotic oscillation's parameters are considered. The system transferring into dynamical chaos mode is implemented by introducing of irregularity into generator's output transmission line. It is shown, that control of the main radio engineering parameters of the generated microwave chaotic oscillation may be carried out by adjustment of the IMPATT diode supply current and changing the frequency dependence of the reflection coefficient from irregularity introduced into the generator's output transmission line.

Enhancement of avalanche noise in IMPATT diodes due to E-E and H-H collisions

Abstract: The effect of energy-loss due to electron-electron (e-e) and hole-hole (h-h) collisions on the avalanche noise performance of IMPATT diodes has been studied. Simulations have been carried out on DDR Si IMPATTs operating at 94, 140 and 220 GHz. Simulation results show that the noise measure of the diodes considerably increases due to e-e and h-h interactions within the space charge layer of the device. This is observed to be more influential at higher mm-wave frequencies.

A sensitivity analysis of millimeter wave characteristics of SiC IMPATT diodes

Abstract: Ionization rate coefficients and saturation drift velocities for electrons and holes are the vital material parameters in determining the performance of an IMPATT diode. We have performed a sensitivity analysis of the millimeter wave characteristics of 4H-SiC and 6H-SiC IMPATT diodes with reference to the above mentioned material data and an operating frequency of 220 GHz. The effect of a small variation in the ionization rate and drift velocity on the device characteristics like break down voltage, efficiency, noise measure and power output has been presented here.

A JL-SDR-IMPATT Device with Improved Efficiency

Abstract: An attempt has been made to present a new device which will function as a highly efficient SDR (Single Drift Region) P+-N-N+ IMPATT diode utilizing the advantages of a junctionless field effect transistor. The basic idea is to convert a uniform N+ region into a (P+–N–N+) structure without any requirement of physical doping. As the present device works on the principle of a junctionless channel, variability and short channel effects are significantly reduced as compared to the conventional TFET though the requirement of an extra gate increases a few fabrication steps. Further, efficiency more than conventional SDR IMPATT diode is achievable without any physical doping.

The transceiver tract influence on the characteristics of positioning systems with a chaotic probing signals

Abstract: In this paper the investigation on the special aspects of usage of broadband chaotic signals in the systems of precise positioning and radiolocation is done. The results of the numerical experiment on the investigation of the influence of the productivity of the analog-digital converter (ADC) and additive white noise in the radio channel on the performance and working efficiency of the system are presented. As the probing signal the real chaotic microwave broadband signal is used, generated as the result of the experimentation with a microwave generator of chaotic oscillations based on IMPATT diode. The results of comparison of resistance to destabilizing factors of the two main methods of processing of chaotic probing signals are discussed. These are the correlation method and the method of double spectral processing.

Terahertz Properties of GaN/AlGaN Heterostructure IMPATT Diode

Abstract: The terahertz properties of a Double Drift Region (DDR) heterostructure IMPATT diode, based on GaN/A1GaN, are simulated for operation around 0.5 THz. The device DC to RF conversion efficiency of 17.1% and a noise measure of 21 dB, expected from the heterostructure GaN/A1GaN IMPATT diode, are noteworthy.

Effect of optical illumination on DDR IMPATT diode at 36 GHz

Abstract: A reverse biased p–n junction diode with proper resonant cavity and boundary conditions is able to generate rf power and shows normal DC and small signal properties designed with semiconductor materials like 4H-SiC, GaAs, InP, Si-based DDR IMPATT structure at Ka band with dark condition. But when it is exposed to optical illumination through a proper optical window for both top mounted (TM) and flip chip (FC) configuration, it shows the influence on the oscillator performances in that band of frequency. The simulated results are analyzed for 36 GHz window frequency in each of the diodes and relative differences are found in power output and frequency of all these diodes with variable intensities of illumination. Finally it is found that optical control has immense effect in both FC and TM mode regarding the reduction of output power and shifting of operating frequency from which optimization is done for the best optically sensitive material for IMPATT diode.

generated by photoexcitati on subsequently take part in the avalanche multiplication process.

Abstract: in which Abstract This paper reviews the variety of ways in which optical signals have been used to control microwave devices in such applications as optical-injection locking, phase shifters, modu­ lators, and switches. Techniques for the generation and detection of microwave radiation by optical means are also described. The feasibility of optical microwave monolithic inte­ grated circuits is considered. In this paper, various techniques for the optical control of microwave devices are reviewed and evaluated. Many of these techniques have not yet been realized in monolithi- cally integrated form, but have be.en demonstrated in discrete or hybrid configurations. Never-the-less, the same basic principles apply, and monolithic integration will most likely soon follow. The optical control functions that can be performed generally fall into one of four subclasses, optical-injection phase locking of microwave oscillators, optical phase shifters, modulation or switching of microwave signals by optical beams, and the generation and detection of microwave signals by optical means. The use of optical, rather than electrical, control signals in many cases provides improved coupling, higher speed of response, and maximum isolation. Optical injection locking IMPATT diode oscillators are used in many microwave and mm wave applications because of their relatively high-power, high-frequency capabilities. However, they have a tendency toward output frequency instability that arises from the highly nonlinear, temperature- sensitive avalanche multiplication mechanism inherent in their operation. For example, Kuno and English have reported a frequency decrease of 2.75 MHz/°C in the 60 GHz range. Injection of a microwave control signal from a more stable oscillator can be used to over­ come that (.problem. Prior to 1977, this was accomplished by injecting an electrical signal. ' More recent work has shown that an optical beam can be used both to switch and to phase lock IMPATT diodes, and other microwave oscillators as well. The optical control signal is usually generated by appropriately modulating a GaAs or GaAlAs laser diode, and is introduced into the IMPATT by either directly focusing the light onto thep-n junction depletion region, or coupling it via an optical fiber waveguide. The reverse biased IMPATT diode acts, in part, as a depletion layer photodiode. Carriers generated by 'photoexcitation subsequently take part in the avalanche multiplication process.

Performance of 4H-SiC and Wz-GaN Over InP IMPATT Devices at 1.0 THz Frequency

Abstract: We have studied the performance of impact avalanche transit time (IMPATT) devices based on wide band gap semiconductor materials like 4H-SiC and Wz-GaN over low band gap InP at 1.0 tera-hertz (THz) frequencies. A drift-diffusion model is used to design double drift region (DDR) IMPATTs based on these materials. From the results, it is found that the RF power for 4H-SiC gives 26 times more than InP and 4 times than Wz-GaN based IMPATT diode. Similarly, the Wz-GaN has more noise of about 32.6 dB as compared to 4H-SiC (29.5 dB) and InP (31.5 dB). Generation of significant RF power for 4H-SiC with moderate noise is better as compared to the InP and Wz-GaN based devices. The excellent results indicate that 4H-SiC based IMPATT diodes are the future terahertz sources.

Noise Estimation of Heterostructure GaAs/GaP Over Homostructure GaAs and GaP Based IMPATT Devices at 94.0 GHz Frequency

Abstract: The potential of heterostructure based impact avalanche transit time (IMPATT) devices have been studied and compared with homostructure diode. We have studied the simulation results of DC, SS and avalanche noise estimation of new types of materials combination GaAs/GaP heterostructure and the results are compared with the homostructure GaAs and GaP materials. The diodes are design to operate at the millimeter-wave frequencies of 94 GHz. A drift-diffusion model is used to design double drift region (DDR) IMPATTs based on these materials. The simulation results of these diodes shows that GaP based IMPATT diode gives better performance in terms of RF Power as compared to other diodes. It is interesting to observe that the mean square noise voltage for GaAs/GaP is very less as compared to GaAs and GaP.

Millimeter-wave and Sub-THz Signal Generation and Detection in Silicon Technologies

Abstract: Author(s): Nazari, Peyman | Advisor(s): Heydari, Payam | Abstract: MM-wave/sub-Terahertz(THz) signal generation, radiation and detection has become increasingly attractive due to its fast-growing applications in spectroscopy, radar, biomedical and security imaging as well as high-speed wireless communication. Silicon technology, in one hand, offering high-density signal processing capabilities due to aggressive scaling of its feature size, and on the other hand, allowing integration of mm-wave/THz antenna elements owing to their shrunk footprint at these bands, is well-suited for implementation of fully-integrated multi-antenna mm-wave/THz wireless System-on-Chips (SoC's). Performance of such system is dominantly governed by the quality and efficiency of signal generation, transmission/reception and detection. Passive and active components as means of realizing these functionalities must be optimized for operation at these frequency range. However, excessive loss of on-chip passive components and limited gain and output power of transistors at such high frequencies demand novel passive and active structures. Furthermore, high level of integration implies that the co-design of front-end components leads to a better end-to-end performance, thus a holistic design methodology must be employed. Radiation characteristics of the wireless signal must also be engineered to improve its transmission quality. For example, circularly polarized radiation is found to be a viable choice for many imaging and communication applications by exhibiting excellent robustness against de-polarization effects.In this dissertation, silicon realization of on-chip waveguides, as low loss mediums for high-frequency wave propagation, is explored and implementations of low-loss cavity-backed passives are discussed. Furthermore, a silicon-integrated IMPATT diode, together with its fabrication and modeling is introduced as a solution for obtaining active behavior beyond $f_{max}$ of transistors. Next, a high-power/efficiency mm-wave circularly-polarized cavity-backed radiator, employing a multi-port multi-function passive network as resonator, power combiner, and antenna, is introduced. Necessary conditions for robust operation of such multi-port oscillators/radiators are also derived. Fabricated in a 0.13$\mu$m SiGe BiCMOS process, the prototype chip achieves 14.2dBm EIRP, -99.3dBc/Hz phase noise at 1MHz offset, and 5.2\% DC-to-EIRP conversion efficiency which is the highest reported value among silicon-based radiators not using silicon lens or substrate processing.Finally, a 210GHz low noise amplifier (LNA) is presented to address the detection challenges. This LNA, achieves 18dB of gain, with less than 12dB noise-figure and 3dB bandwidth of more than 15GHz, thereby showing best performance metrics among prior work. This is achieved by incorporating circuit and EM techniques enabling simultaneous optimization of stable gain-, noise- and bandwidth-performance parameters at this frequency range.

Development of MATLAB Based Image Stitching Tool for Detection of Hidden Objects at 89 GHz

Abstract: Our system uses a 108 mW IMPATT diode source operating at 89 GHz, a 45 cm × 45 cm detector camera from TeraSense and a motorized XY stage covering 34 cm × 22 cm area Hidden objects having large dimensions can be imaged using small area detector using this technique in 10–11 min Image stitching and enhancement is done using MATLAB and imageJ software programming