Transistor switches driving in ADS-B / mode 4 amplifiers

Design process of highly efficient means of communication, surveillance and navigation using switch-mode amplifiers requires a revision of traditional approaches to the circuitry of radio transmitting devices. The parameters of the physical layer of ADS-B systems using VHF datalink mode 4 (VDL-4) theoretically allow the use of switch-mode amplifiers as part of their transmitters. Such an improvement plays a particularly important role in the context of integrating unmanned aerial vehicles (UAV) with limited energy reserves on board into the general airspace.One of the important tasks in the design of such radio technical support for flights operating in the VHF range (primarily onboard, but also ground-based) is to determine approaches to control transistor switches of a power amplifier based on the criteria of efficiency, stability and the ability to provide different operation modes of the switch-mode amplifier. Requirements for the control device have been developed taking into account the standard for the physical layer of VHF datalink mode 4. A conclusion is given on the optimal solutions suitable for building a VDL-4 transmitter with a switch-mode power amplifier, opening up prospects for increasing the efficiency of more than 90%, compared to today’s not exceeding 46%.