Timur T. Gazizov

Influence of ultrashort pulse duration on its peak values localization in PCB of spacecraft autonomous navigation system

Importance of research on specific aspects of ultrashort pulse propagation and voltage peak values localization along printed circuit board (PCB) multiconductor bus is highlighted. Simulation of a trapezoidal ultrashort pulse propagating along conductors of the bus with a different number of excited conductors, fixed variation of the whole ultrashort pulse duration (3; 0.3; 0.03 ns) and a duration optimized by genetic algorithms has been carried out. In the case of one excited conductor, the maximum value exceeds by 18% the ultrashort pulse amplitude at the input and the greatest (by modulus) minimum value is −36% of 0.5 V level lower the level of zero. In the case of two conductors, the highest maximum value exceeds by 20% the ultrashort pulse amplitude at the input and the minimum is −40% of 0.5 V level lower the level of zero. It is shown that significant signal excess is observed with decreasing of ultrashort pulse duration both for maximum and minimum. Also, localization of voltage peak values is inconstant: they appear in different parts of PCB bus including different PCB layers. With the usage of optimization, a voltage maximum in the given conductor exceeds the 0.5 V level by 16%, when the whole duration of an ultrashort pulse is near 0.13 ns.

Optimization of parameters of multiconductor modal filters for protection against ultrashort pulses

Paper considers improvement of the protection against ultrashort pulses by means of optimization of parameters of multiconductor microstrip lines by different criteria. We have obtained a three-conductor microstrip line with the maximized difference of delays between the first and the last decomposition pulses. It was achieved by means of expansion of time intervals between decomposition pulses. At the same time, signal amplitude at the output of a line considerably decreases (almost twice). The results have shown that it is important to optimize multiconductor modal filters considering both minimization of amplitude of an output signal and maximization of difference of delays between the first and the last decomposition pulses.

Experimental confirmation of the modal filtration in four- and five-conductor microstrip lines

An experimental confirmation of modal filtration based on multiconductor microstrip lines is executed. Authors designed four- and five-conductor prototypes of modal filters (MF), which have the maximum amplitude of the decomposition pulses of 12.6 and 15.3 times less in comparison with the initial signal. The results showed the prospect of research of multiconductor MF because addition of conductors to the initial structure additionally (up 2.3 times) decreases the amplitude of the initial signal at the end of the active conductor.

Optimization of three-conductor microstrip line modal filter by heuristic search and genetic algorithms

The improvement of the protection against ultrashort pulse (USP) through the use of modal filters (MF) is considered. A review of researches dedicated to MFs based on multiconductor microstrip line (MSL) is made. A MF on the basis of a three-conductor MSL is investigated. Optimization of conductors separations in a MF is executed in two ways: heuristic search and genetic algorithm (GA). After optimization by using the GA we obtained an amplitude of USP at the output of MF that is 13% less than the one after heuristic search. It is proposed to use these methods successively.

Optimization of ultrashort pulse duration with usage of genetic algorithms by criteria of peak voltage maximization in PCB bus

Importance of the genetic algorithms (GA) usage in the investigation of an ultrashort pulse peak voltage in multiconductor structures of printed circuit boards (PCB) is highlighted. Trapezoidal ultrashort pulse propagation along the conductors of a real PCB multiconductor bus was simulated. Using GA an optimization of the whole ultrashort pulse duration and separately of the rise, top and fall durations was made by a criterion of the peak voltage maximization in the PCB bus. A voltage maximum which is revealed with the whole ultrashort pulse duration variation by 16% exceeds the steady state level when the whole duration is near 0.13 ns. A voltage maximum exceeding the steady state level by 36% is revealed and localized by using the variation of ultrashort rise, top and fall durations. The maximum crosstalk value of 24% of the steady state level is observed for this case. For the last voltage and crosstalk maximums, the whole ultrashort pulse duration is near 1 ns. A good replicability of results is shown.

Multicriteria optimization of multiconductor modal filters by genetic algorithms

Multicriteria optimization by genetic algorithms is considered. We optimize novel devices for the protection against ultrashort pulses referred to as multiconductor modal filters (MF) by means of the decomposition of the pulses into a sequence of smaller pulses. A multicriteria objective function with amplitude and time criteria is formulated. Five amplitude criteria are proposed for the critical systems, as well as range-time and interval-time criteria. To test the theory, four-criterion optimization of four parameters for a three-conductor microstrip MF has been performed. The results have shown the importance of optimization of multiconductor MF with the simultaneous use of several criteria: the three-conductor microstrip MF with attenuation factor of 21.4 times for ultrashort pulse with the duration of less than 0.6 ns/m is obtained.

Delay line protecting against ultrashort pulses with increased duration

The paper shows the possibility to increase the duration of ultrashort pulse which can be decomposed in the one turn meander delay lines. For this purpose, we suggested a condition that increases duration of ultrashort pulse up to a value that is equal to twice the product of the minimum of per-unit-length delays of even and odd modes of a signal and the length of half-turns. Simulation showed the expansion of ultrashort pulses with increased duration when this condition is fulfilled. It has been revealed that such decomposition without proper optimization results in the increased amplitude of the output signal. Therefore, an additional optimization was made to provide additional reduction of the amplitude of ultrashort pulse resulting in 32% of input signal.

Influence of losses on ultrashort pulse decomposition in a turn of meander microstrip line

The paper analyzes influence of conductor and dielectric losses on the ultrashort pulse decomposition in a turn of meander microstrip line. The investigations revealed that losses in conductor have more significant influence on the amplitude and form of a pulsed signal than losses in dielectric. It is also shown that losses in conductor have more influence on the amplitude of odd mode pulse, while losses in dielectric have more influence on even mode pulse. However, complete consideration of losses has shown that losses significantly change only the odd mode pulse, while the crosstalk pulse and the even mode pulse are changed insignificantly. A noteworthy effect has been revealed: overlong fall of the second pulse (because of losses) is added to the third pulse and, thus, its amplitude is increased and delay is reduced. At last, it is shown that consideration of losses can reduce the optimum coupling between conductors by the criterion of minimal amplitude of the output signal.

Method of lay-out of multilayer PCBs for circuits with redundancy

A new method of lay-out of multilayer printed circuit boards for circuits with redundancy is considered. A structure with two conductors is considered; in this structure the initial interference pulse is decomposed into two pulses with fourfold lower amplitudes. The paper demonstrates the effect of the relative dielectric constant value of the sublayer between redundant and backup conductors on difference between per-unit-length delays of even and odd modes. The difference can change a sign and multiply the absolute value. Furthermore, increase of coupling between conductors decreases the amplitude of the output signal. The obtained results prove that the proposed method allows to increase interference immunity of the redundant circuits in multilayer printed circuit boards.

Parametric optimization of protective meander line turn in air filling by genetic algorithm

One-criterion parametric optimization by genetic algorithm (GA) of air protective meander line turn cross-section is executed. For this task the quality function which provides geometric mean of wave impedances for even and odd modes of the line (Z) to be equal to the 50 Ω is formulated. All of 4 cross-section parameters of the investigated structure are simultaneously optimized. The results of 5 GA runs with 10 and 100 generations of 30 individuals are described. Well reproducibility of Z value around the value of 50 Ω with deviation less than 0.1% is demonstrated. The optimization time costs were estimated. The source code of the program (in TALGAT software) is presented in Appendix.