Dual channel amplifier chain at Ka-Band with controllable phase and amplitude

Abstract

This project is to develop a dual-channel amplifier chain functioning at Ka-band, with adjustable phase and amplitude, a subject of increasing significance in contemporary communication systems that require both high efficiency and consistent performance [1]. The principal issue at these frequencies is the considerable insertion losses of interconnects and active components, alongside the manufacturing and mechanical limits inherent to substrates like FR-4 and the constraints of human assembly. A thorough methodology was employed, integrating theoretical design with electromagnetic-based simulations. The system architecture comprised a power splitter, a mixer for phase and amplitude modulation via an external signal source, pre-amplifiers to mitigate initial losses, and primary power amplifiers capable of outputting power levels approaching 30 dBm. Biassing circuits were meticulously constructed, taking into account electrical stability and manufacturing feasibility to ensure alignment with the fabrication capabilities of the chosen PCB manufacturer. The simulation findings confirmed the viability of accurate phase and amplitude control via the mixer’s external input, while also illustrating good loss compensation and stable overall performance. The nonlinear distortion products produced by the mixer were demonstrated to be insignificant, validating the design's robustness. Conversely, the mixer step remained a notable source of loss, indicating potential for enhancement through the utilisation of superior components or different design methodologies. Notwithstanding these achievements, many limits must be recognised, including the hazards linked to human soldering of fine-pitch components and the possible discrepancies in trace shape resulting from fabrication tolerances. These limits, however, do not diminish the project's achievements but rather indicate opportunities for improvement in future endeavours. Possible enhancements are utilising sophisticated substrates like Rogers RO4350B or employing automated precision assembly techniques to reduce variability and improve uniformity. This project exemplifies a feasible and executable architecture that substantiates the concept of phase and amplitude control at Ka-band. It establishes a robust basis for the advancement of more efficient outphasing-based RF systems, representing a significant progression towards next- generation communication technology.