This article is a continuation of the topic consideration of reverse intermodulation distortions (RIMD) analysis begun by the authors in [1] for class D RF power amplifiers (PA) with a resistive load in the voltage switching mode (Voltage Mode Class D - VMCD). In this article, a theoretical analysis of RIMD in class D RF PA with a resistive load in current switching (CMCD) and bridge (BMCD) modes was carried out. A comparison of the various circuits parameters requirements in order to achieve a given RIMD level not exceeding minus 70 dB showed that: - the VMCD circuit imposes the most stringent requirements for all influencing parameters: the switches saturation resistance variation should not exceed 20%, and the total switches saturation time deviation in any combination should not exceed 0.01, which is 2% from half a period; - the CMCD circuit allows a similar switches saturation time deviation, but the distortion in it does not depend on the difference in switches saturation resistance; - the BMCD circuit allows a 70% difference in the switches saturation resistance. The permissible total switches saturation time deviation depends on the operation mode and is 2.4% for overlapping and 18% for undercovering. The choice of the class D RF PA configuration used in a particular application is based on a large number of factors - efficiency, power level, the ability to work with collector (drain) modulation in a wide frequency range, resistance to load mismatch, element base, etc. The conducted research allows developers to take into account one more parameter - resistance to induced electromagnetic radiation.

Reverse Intermodulation Distortion in Current Mode and Bridge Class D RF Power Amplifiers

In this paper we discuss the problem of dynamic measurements of digital measuring device for on-board radio electronic equipment. For such a measuring device, when a moving object moves under conditions of influencing noise, the accuracy of measurements decreases. The problem of increasing the accuracy of such dynamic measurements is considered. This article proposes the method for increasing accuracy for on-board radio electronic digital device applied at the moving object with on-board electronic equipment. Theoretical consideration of the accuracy of navigational determinations of the onboard measuring device under noise conditions and taking into account the object's movement dynamics is carried out. The article provides a theoretical analysis and computer simulation of the considered digital measuring device for on-board radio electronic equipment. It has been found that when combining on-board navigation and radio communication facilities are usually used to improve the accuracy of navigation determinations by implementing differential operating modes, it is possible to improve the accuracy of dynamic measurements.

Dynamic Measurements Accuracy Increasing of Digital Measuring Device for On-Board Radio Electronic Equipment

The article is devoted to the possibility of implementing a receiver of multi-frequency Cp-FSK signals. To obtain a stream of digital samples, the use of a software-defined radio (SDR receiver) is considered. For demodulation, it is proposed to use single-board PCs with ARM architecture processors and graphic processors. The use of GPUs allows the use of computationally efficient digital filter bank algorithms to receive multi-frequency Cp-FSKs. The article considers the implementation of the reception of a signal-code structure based on multi-frequency signals and non-binary error-correcting codes. The proposed device can be used for UAV command telemetry radio links.

Implementation of M-CpFSK Signal Reception Using ARM Processor with GPU and SDR Receiver

In this paper, we prove a theorem on the well-defined solvability of a boundary value problem in the middle of the domain and make some generalizations so that local and nonlocal boundary value problems for hyperbolic equations with a third-order dominant mixed derivative are generalized by the statement. 

Some General Classes Well-Posed Three-Dimensional Boundary Value Problems in the Middle of the Domain for Hyperbolic Equations

During the primary coding, certain numbers are assigned to the elements of the original message, usually in binary form. Thus formed code combinations of $n$ binary symbols differ from each other by a certain code distance $d_{ij}$ . Among the most well-known methods of primary coding, we note the weighted (natural) code and the Gray code. The purpose of this article is to develop a method for constructing a primary code with given code distances between adjacent code words. This article also discusses the problem of choosing a primary coding method from the point of view of minimizing distortion of the restored continuous signal under the influence of interference in the communication channel and the occurrence of errors caused by them in the discrete signal.

Construction of the Primary Code with the Specified Code Distances between Adjacent Code Combinations

Increasing the efficiency of transmitters, as the largest consumers of energy, is relevant for any wireless communication devices. For higher efficiency, a number of methods are used, including envelope tracking and envelope elimination and restoration. Increasing the bandwidth of used frequencies requires expanding envelope modulators bandwidth up to 250–500 MHz or more. The possibility of using amplifiers with input signal quantization (AISQ), as an alternative to the most common hybrid envelope tracking modulators, is considered. An approach has been developed for optimizing AISQ characteristics according to the criterion of minimum loss when amplifying modern telecommunication signals with Rayleigh envelope distribution. The optimal quantization levels are determined and the energy characteristics of AISQ are calculated. AISQ loss power is shown to decrease by 1.66 times with two-level quantization, by 2.4 times with three-level quantization, and by a factor of 3.0–3.7 for four–five quantization levels compared to a class B amplifier. With these parameters, AISQ becomes competitive with respect to hybrid envelope tracking modulators but does not have electromagnetic interference from the pulse width modulation (PWM) path.

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Dang Canh Nguyen

Papers

Broadband and Efficient Envelope Amplifier for Envelope Elimination and Restoration/Envelope Tracking Higher-Efficiency Power Amplifiers