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The quadrature modulators and demodulators are widely used to create modern wireless communication systems. It is important to ensure high quality of the transmitted signals in order to have the exchange of information without loss or failure. From the point of view of the spectral decomposition of the signal (Fourier series decomposition), the useful component of the spectrum must be much larger than all other components. The carrier (LO frequency and spurious sideband are the most critical and undesirable quadrature modulator output signal spectral components. In the work, in the course of the research using the methods of suppressing the parasitic components, based on minimizing phase, amplitude and current imbalances in various nodes of the quadrature modulator circuit, have been revealed. In order to realize suppression, the special digital-to-analog converters are used in conjunction with a polyphase filter on varicaps, a phase-shifting block and current sources. The effectiveness of these methods is confirmed by the achievement of suppression of parasitic components in prototypes of 50 dB or more. It has been stated that the phase unbalance minimization is more effective than the amplitude unbalance minimization to sideband suppression. It has been revealed that the use of a phase-shifting block is a more suitable architecture to control the phase unbalance. The obtained results can be useful in the design of high-precision radio frequency units for various purposes.
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The process and device simulation tools features have been analyzed. The tools have been analyzed applied to the calculation of electrical characteristics for various integrated circuit devices, operating in different external conditions. The model features having the maximum effect on the simulation results have been revealed.
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Some specific features of the device-technological simulation have been considered. The results of the simulation and optimization of the integrated magnetosensitive elements as a part of micro- and nanosystems have been considered. The results of the simulation and optimization of the constructive -technological parameters for magnetosensitive transistors, Hall integrated elements, formed within the CMOS technology standards and the field Hall sensor based on the SOI technology as well as the characteristics of magnetic field concentrators have been presented.
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Self-heating effects and heat sink problems in lateral power SOI-MOSFET's have been studied. Using the process and device simulation TCAD tools the output characteristics and safe operation area have been simulated. It has been shown that the safe operation area limitations to higher extent are related with the structure self-heating than with the parasitic bipolar transistor turning on.
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It is necessary to reduce the configuration bit stream volume if there is a need to write several FPGA configurations to the ROM. This leads to decrease in the topological size of the ROM block on the chip. The article discusses the development of the mechanism of compression and decompression of the FPGA configuration bit stream. It has been shown that the stream of configuration data has some regularities. This is due to the presence of a large number of «forbidden» states in the configuration data set, when inadmissible connections of logical elements are formed. The algorithm of compression and decompression of the FPGA configuration bit stream has been proposed. The algorithm is based on the analysis of the FPGA architecture and the compilation of the conversion table using the prefix code commands. The advantage of the algorithm is the search for the most repetitive combinations based on the analysis of the FPGA architecture, instead of searching for the entropy of a random set of configuration data. Another advantage is the relative simplicity of the decoding algorithm, which saves hardware resources for the implementation of the decompression mechanism.
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There are certain difficulties in the development of a broadband generator of quadrature signals (QSG) on a SiGe BiCMOS technology. The problem of linearity and broadband matching is the most difficult to solve. When designing QSG in a wide frequency band, there is a problem of forming a quadrature signal using traditional solutions using a polyphase filter or a digital D-trigger. The use of only one method for forming a quadrature signal is impossible due to the limiting features of the electronic component base of SiGe BiCMS technology. To solve this problem, we propose a structure that allows us to develop a broadband quadrature signal generator with an operating frequency range from 10 MHz to 6 GHz, using the method of dividing the operating frequency band. At frequencies from 1 to 6 GHz, the quadrature signal is generated using a polyphase filter, and at frequencies less than 1 GHz using a frequency divider. Using this method, the following characteristics of the FCS have been achieved: the difference in the amplitudes of quadrature signals is less than 0.3 dB; the VSWR is less than 1.6 over the entire frequency range; the transmission coefficient is not less than -2 dB at a 0 dBm heterodyne power; at a frequency of 6 GHz P1dB of at least 3 dBm. The experimental results are in good agreement with the simulation data.
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The results of the studies on the scanning electrical-conductivity Transport Properties have been shown. The correlation of the required pressing force on the conductive cantilever to the surface, which provides a close contact with the test sample, with the material hardness and the thickness of the cantilever conductive coating, has been revealed. It has been shown that while investigating at higher values the potential difference on one hand, it is necessary to take into account the possible effect of the conductive coating material redistribution from the cantilever to the sample surface, on the other hand- the ability to provide the higher resolution while investigating the sample topography by conductive cantilever.
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The mechanism of the impurity carbon on boron diffusion of the n - p - n SiGe HBT’s base has been considered. Some figures demonstrating the dependence of electrophysical characteristics of the structure on the carbon concentration have been presented. It has been shown, that at the carbon concentrations exceeding 1· 10 cm a charge carriers lifetime decline has been observed, but this does not result in the decrease of the cut-off frequency and maximum HBT oscillation frequency, because of the less intensive boron diffusion, determining the neutral base transient time.
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