Status of a C-band Phased Array Feed with RFSoC digital beamformer

In this paper, we describe the design and development status of a room-temperature C-band Phased Array Feed (PAF) demonstrator, based on Radio Frequency System-on-Chip (RFSoC) for radio astronomy application, to be installed on the Sardinia Radio Telescope. The instrument is optimized to work across the 4.75-6.00 GHz radio frequency (RF) band. The project of the front-end includes a compact RF module based on an 8×8 array of linear dual-polarization antenna elements integrated with Monolithic Microwave Integrated Circuit (MMIC) Low Noise Amplifiers (LNAs). In the preliminary version of the front-end project, which considers only one linear polarization, a subset of 32 elements are connected to the LNAs, while the rest of them are terminated to 50 Ohm matched loads. A dedicated signal acquisition chain of microwave components, based on two stages of filtering and signal conditioning, permits the injection of the 32 RF signals to the two commercial back-ends based on RFSoC digital boards. Each board is equipped with 16 inputs, with 1.25 GHz instantaneous bandwidth, and performs the frequency channelization, the partial and final beamforming of at least four independent beams (the number of beams may vary depending on the observation requirements). A general description of the front-end design, the back-end hardware, firmware and software development and an optimizer for the whole system performances evaluation, is presented.