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This master thesis deals with the problematics of CT filters and focuses on Gm – C filter. Three linearisation techniques are listed and compared in terms of linear input range, distortion and retuning. In the practical part – second - order low – pass filter is designed and its tuning capabilities are examined.

The state-variable analog filter topologies are described. Using the transfer function theory and operational configurations suitable for integration and derivation, a new universal filter topology are proposed. The circuit has been implemented in CMOS technology by using six operational amplifiers, eight analog switches and five programming resistor array. Tunable corner frequencies, quality factors and gain are realized. Using the serial peripheral interface or digital memory can be realized this real-time digitally programmable first- and second-order analog filter with the tunable parameters.

This master’s thesis deals with the design of tuneable frequency second order filter in CMOS technology. The thesis describes the design of a transconductor and its utilization for tunable gm-C filter. The design and all simulations were made in Cadence Spectre and Virtuoso software. Limitedly Orcad Pspice and SNAP were also used.

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Ultrasound investigation is one of meaningful imaging at present. Advantages of ultrasound are, that it hasn´t side effects as a rtg radiation and it is noninvasive. Ultrasound diagnostic is exploited in all branch of medicine (urology, cardiology, orthopeadist, gynecology etc.) to display organs, tissues and cavities of the human body. We use display in 2D, 3D and most modern display in 4D. We can encounter with many kinds of artifact. Artifacts are described more closely at 3rd chapter. Speckle noise deteriorates informative yiled of ultrasound picture. We try to remove speckle noise by simpler methods or more complex methods of filtration. These methods are described at 5th chapter. Programme for speckle filtering from pictures is part of this master´s thesis.

This work analyzes tuning capabilities of different fully integrated active filter topologies. Work only deals with continuous time active filters. Topologies described in this work differ in type of active element and in method of frequency tuning. Techniques of tunning are proved on second order low pass filter. Filter topologies are compared from tunning capabilities and from point of total harmonic distortion. The main building block of all filters is integrator.

In this paper it is illustrated that currently there is a new element in electronics - fractional order filter consisting of fractal devices. The circuits selected are presented and analyzed in this diploma thesis. The calculation of the basic characteristics and parameters of the filter of fractal elements was made. An analysis of the functions and their graphs were presented. The simulation of fractional-order filter for its design was made in the program Matlab. The graphs of frequency characteristics (magnitude and phase response) were obtained in the program OrCAD. The examples of using this fractional order filter are described.

Aim of the thesis was to evaluate the influence of fish stock on the hydrochemical parameters of the water in Recirculating systems. A part of the work was elaboration of the literature review on the topic. In the experimental part was performed several trials under laboratory and practical conditions. The first trial aimed on comparison of hydrochemical parameters between recilculating system with biological filtration and recirculating system without biological filtration. There was studied a content of nitrogen compounds. The content of ammonia nitrogen was higher in the system without filtration (0.2 -- 1.0 mg.l-1) than in the system with biological filtration (0.1 -- 0.4 mg.l-1). In the system with the biological filtration was higher a content of the nitrite nitrogen ranged from 0.14 to 0.16 mg.l-1. In the system without filtration ranged content of nitrite nitrogen from 0.01 to 0.1 mg.l-1. In the next trial was monitored a development of the hydro chemical parameters in recirculating systems after their launch. Two monitoring was made. In the first three weeks was observed increased content of ammonium nitrogen, after its reduction increased nitrite nitrogen. These compounds were sufficiently degraded roughly after a one month. The third trial was aimed on changes in recirculating systems during 24 hours. Monitored were contents of nitrogen compounds, oxygen and pH. The lowest content of ammonium nitrogen was registered at night. The biggest increase of ammonium nitrogen was found after feeding of the fish. Content of nitrite nitrogen increased during monitoring due to biological degradation of ammonium nitrogen in filter. The biggest decrease of oxygen was registered after fish feeding. Oxygen decreased op to 10 percent. The pH continuously decreased during monitoring due to CO2 production of fish and biological processes in filter.

This thesis dealt with evaluation of particular types of filtration devices. It highlighted their advantages but mentioned their weaknesses as well. In the theoretical part of the thesis there was a description of all the filter types available on the Czech market, whilst the practical part was focused on comparison of two seleceted filters - plate filter DF 200*200 mm with drain board and cross-flow fiter Romfil RF2C. The measurement result showed that cross-flow filters were more powerful with their performance about 2 530 litres per hour. Concerning microbial stabilty both filter types showed the same efficiency. The thesis also contained comparison of both filter types operating costs. According to the model calculations it was obvious that with using cross-flow filter the filtration costs were lower - around 0,30 Kč per 1 liter of filtered wine (considering 150 working hours per year). filtration costs with using plate filter were around 0,50 Kč per 1 liter (considering the same working hours).