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The paper deals with a new efficient method for test frequency selection for analog fault diagnosis based on a transformed space of optimization coordinates. The original symmetrical linear space is transformed so that the mirrored optima are removed and the transformation takes into account the logarithm scale of the frequency axis. The optimum set of frequencies is found faster and the optimization...
The paper deals with an interesting oscillator solution derived from LC Colpitts circuit structure. Electronically controllable current gain of the current amplifier is utilized for driving of oscillation condition together with two transconductances in frame of voltage differencing transconductance amplifier for adjusting of frequency of oscillation. In the proposed structure these elements replace...
The paper deals with a multifrequency parametric fault diagnosis of linear analog circuits. The method can estimate the actual values of some network parameters. The components whose parameters are outside allowed tolerance intervals are classified as faulty. The parameter estimation process based on square system of equations uses measurements at several test frequencies while the rest of the frequency...
Our contribution discusses modification of well-known Colpitts LC oscillator to fully electronically controllable type utilizing adjustable current amplifier and inductance simulator based on voltage differencing transconductance amplifier (VDTA) instead of common bipolar transistor and passive metal coil. Implementation of current amplifier allows independent and direct control of oscillation condition,...
Quite neglected and underlying problem of modern active functional blocks is presented and demonstrated in this contribution on a current-mode active filter. The discussed problem is an undesirable transfer in stop band of multifunctional frequency filters. It is caused by several occasions related to small-signal parameters of active elements (impedance levels) in the circuit. In some cases it leads...
The paper deals with the design of a test link for the characterization of a hybrid Free Space Optical/Radio-Frequency (FSO/RF) atmospheric channel. The ever-increasing demand on broadband connectivity, specifically in the Last-Mile networks, leads to the use of Free-Space optical systems in combination with RF systems above 100 GHz, which are able to reach data rates in the order of 10 Gb/s. However,...
The paper deals with the parametric fault diagnosis of linear analog circuits in the frequency domain. The testability degree, which is referred to as the total number of testable network parameters, is theoretically independent of nominal values of network parameters, the set of test frequencies and the fault detection method. However, practical results show that the effective testability determined...
The paper shows a procedure for testing linear analog circuits using multi-frequency parametric fault diagnosis. Some methods for test frequency selection determine the total number of test frequencies equal to the total number of tested network parameters. The error between actual and estimated network parameters is evaluated only on several frequencies while the rest of the frequency band of the...
The paper shows a procedure for testing large analog circuits or circuits with parasitic parameters via multi-frequency parametric fault diagnosis. To simplify and accelerate calculations the approximate symbolic analysis is used and unknown tested parameters are analyzed in separate frequency bands. Classification of unknown parameters into frequency bands is based on sensitivities. The proposed...
Controllable oscillator based on adjustable current active elements and voltage buffer is presented in the paper. Signal flow graph method employing lossless and lossy integrator synthesis and nonstandard approach for adjusting of oscillation condition based on controllable current feedback are used. The work is focused on analysis of parasitic influences affecting real behavior of the circuit. Expected...
Standard methods for the selection of an appropriate set of test frequencies in multi-frequency parametric fault diagnosis are based on maximizing the conditionality of Jacobian matrix. Due to component failures, manufacturing tolerances, aging and temperature drifts the actual values of components may be different from the nominal ones. For this reason, the selected set of test frequencies may not...
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