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Introduction. The general system of parameters, including compression points and intersection points of various harmonics, is unsuitable for devices operating under the influence of baseband pulses (for example, before the modulator in the transmitter, after the demodulator in the receiver). Previously, the authors have developed simple models in the form of nonlinear recursive filters, which give a satisfactory error in describing the response of a wide class of baseband pulse circuits. The system of nonlinear functions of such models can be considered as a new system of characteristics of nonlinear-dynamical baseband impulse circuits, for which it is necessary to develop a method that ensures their measurement with an acceptable error. In the general formulation, this problem is rather challenging; therefore, this article considers only a first-order nonlinear recursive filter. However, the obtained result gives satisfactory results for devices without flat top transient overshoot.Aim. To consider a method for measuring the characteristics of nonlinear-dynamical baseband impulse devices without overshoot on the flat top of the transient response.Materials and methods. The considered recursive filter is represented by an equivalent circuit consist of nonlinear resistive and capacitive elements. Therefore, the task is reduced to measuring their current-voltage characteristics (IV) and charge-voltage characteristics (CVC). IV characteristics are measured at the flat tops of the transient characteristics of the device. Having a certain IV, we obtain the opportunity to calculate the current (and then the charge) of the capacitive element. The experimental study was carried out on the example of a three-stage amplifier with an aperiodic transient response.Results. The transient characteristics of the filter are approximated by the model with an accuracy of no worse than 3.2 %.Conclusion. The considered system of functions can be obtained with a definable error that satisfactory for practice, which allows it to be considered as a new system of parameters for nonlinear baseband pulse devices.

Introduction. Adequate modeling of semiconductor devices with a p–n-junction in reverse bias represents a relevant research problem. The existing quasistatic and non-quasistatic models fail to provide a satisfactory description for the dependence of nonequilibrium charge carrier lifetime on current density. This leads to significant simulation errors (tens of percent) at pulsed broadband signals. Simulation errors arise, because the existing models regard the lifetime as a constant value.Aim. To propose and investigate an equivalent circuit of a p–n-junction considering the dependence of the lifetime of nonequilibrium charge carriers on direct current, with the possibility of its simple integration into CAD.Materials and methods. The study was carried out on the example of a fast recovery silicon diode BAS16J with a p–n-junction manufactured by Nexperia. A modified diode model is proposed in the form of an equivalent circuit that considers the dependence of the lifetime of nonequilibrium charge carriers on the direct current of the p–njunction at high injection levels.Results. The discrepancy between the experimental and simulated curves did not exceed ±9 % under pulsed diode operation. The extraction of parameters in the proposed model is carried out conventionally, from the current-voltage and capacitance-voltage characteristics of the diode.Conclusion. The proposed non-quasistatic equivalent diode circuit can be used when designing radio electronic devices operated at short-pulse broadband signals. The proposed diode model can be easily implemented in modern CAD systems at the user level.

Introduction. Measuring harmonic distortions of a baseband pulse signal constitutes a problem due to the continuous nature of their spectrum. In order to obtain nonlinear distortions of a signal, a comparison should be conducted either of the object’s responses to two different test signals or those of the real object and its linearized model. However, such an approach does not distinguish between various physical factors that cause nonlinear distortions. This, as a result, complicates the optimization of devices.Aim. To develop an approach capable of determining the contribution of various sources to the nonlinear distortion of baseband pulse signals.Materials and methods. The method under consideration involves a synthesis of a nonlinear behavioral model for an object and a comparison of the model’s output signals when linearizing some (or all) of the characteristic functions in this model. This allows distinguishing the contribution of inertialess, capacitive nonlinearity and nonlinearity associated with signal recirculation in feedbacks. An example of a three-stage baseband pulse amplifier (with step functions as test signals) is provided, for which a behavioral model was synthesized in the form of a second-order nonlinear recursive filter.Results. The aggregate signal of nonlinear distortions obtained using the presented method was found to be similar to that obtained by subtracting the responses to two different test signals. Further, the distortions caused by static amplitude nonlinearity, capacitive reactivity nonlinearity and energy recirculation between different reactive storages were distinguished. The nonlinearity of the amplitude characteristic exhibits its effect at the end of the transient process, the nonlinearity with the capacitive nature – at the beginning of the transient process, and the nonlinearity of energy recirculation – in the middle part of the transient process. It is shown that even parts of the nonlinear distortions at step impact, caused by individual physical nonlinearity factors, exceed the harmonic distortions of a RF-pulse signal.Conclusion. The considered method is particularly useful when designing wideband devices with feedbacks, since the nonlinearity of energy recirculation takes effect long after the visual end of the transient process.

Aim: to evaluate efficiency and safety of the combined antihypertensive drug Lozap Plus (50 mg losartan, 12,5 mg hydrochlorothiazide) in patients with arterial hypertension (AH) of I-III grade with high and very high cardiovascular risk. Material and methods: 30 patients with AH of I-III grade (13 men and 17 women aged 51.9±1.9) were observed. Patients received Lozan Plus (Zentiva, Czech Republic) 1 time in the morning during 12 weeks. Ambulatory blood pressure monitoring (ABPM), echocardiography, biochemical blood analysis were carried out, microalbuminuria (MA) was determined, quality of life was assessed. Results: After 2 weeks of therapy decrease in office systolic blood pressure (BP) was observed, and after 4 weeks - in diastolic BP. After 12 weeks of treatment decrease in BP became more significant. Target systolic and diastolic BP was reached in 83.3% and 90% of patients respectively. Decrease in systolic BP was observed in 24 hrs. (from 141.9±1.9 to 128.6±0.8 mmHg, p