Volume 62, Nº 5 (2019)

The article presents the development results of the hybrid-integrated waveguide-planar amplifier circuit for 8-mm wave range with spatial power combining. Affordable and inexpensive low-noise UMS CHA2494-QEC integrated amplifiers are used in the developed circuit. To improve the efficiency of power combining, new longitudinal probe transition designs from a rectangular waveguide to a coplanar strip line (CSL), and to a microstrip line (MSL), whose dimensions do not exceed 0.4λ₀, are proposed. As a result of the amplifier electromagnetic system development, a high efficiency of power combining has been achieved up to η ≈ 85%. The paper presents the experimental results of phase-shift keyed signals transmission through the developed amplifier with a signal level that is slightly lower than the level of 1 dB gain compression. On the basis of the proposed model, the amplifier degradation was also theoretically investigated for various failure modes of one of its active elements.

It is researched a wide class of parametric estimations of power spectral density based on principle of entropy maximum and autoregression observation model. At that there is distinguished the key parameter which is used model order. It is considered a problem of a priori uncertainty when true value of order is a priori unknown. It is proposed a new criterion for definition of order using finite sampling volume with purpose of overcome of the drawbacks of existing algorithms in conditions of small sampling. The principle of guaranteed significance level in a problem of complex statistic hypothesis verification is a basic principle of this criterion. In contrast to criteria of AIC, BIC, etc. this criterion is not related to determination of measurements inaccuracy, since it uses a conception of “significance level” of formed solution only. The efficiency of proposed criterion is researched theoretically and experimentally. An example of its application in a problem of spectral analysis of voice signals is considered. Recommendations about its practical application in the systems of digital signal processing are given.

Now there is a tremendous growth in the specific applications positively related to wireless communications, which posses the specific requirement for mixed-signal integrated circuits. When these independent circuits are used in the unique design of ADC and DAC practical applications, the considerable complexity of the testing increases. BIST is a precisely conventional technique which typically reduces this considerable complexity and prevents functional dependence on high-cost test equipment ATE. Moreover, in Built-In-self-Test (BIST), the output response analyzer (ORA) is the most significant component of architecture of continuous time (CT) sigma-delta analog-to-digital converter (ADC). There are numerous techniques of ORA used for accurate determining the design parameters like integral non-linearity (INL), differential non-linearity (DNL), signal-to-noise ratio (SNR). In this paper, the prime focus is primarily on the modern CORDIC technique which is used as ORA. For the modelling and accurate simulation of this technique Matlab simulink and CADENCE VIRTUOSO EDA tool environment software are properly implemented. A Coordinate Rotation Digital Computer (CORDIC) reduces the design complexity of the independent circuit. The design of ADC can be improved tremendously by typically using BIST. This paper focuses on the system level modelling of test stimuli generator (TSG) and its simulation for accurate characterization of high-resolution sigma-delta ADC. The successful implementation is carefully tested on Matlab simulink tool environment. The auto-testing external test equipment is required to test the integrated structures. TSG is implemented and it helps in extracting of statics and transmission parameters required for characterization of CT sigma-delta ADC.