Development of key technologies of the radio astronomy phased array feed digital backend

Five-hundred-meter Aperture Spherical radio Telescope (FAST) is the most sensitive single-dish telescope in the world. In the past few years since it was put into use, there have been some relatively important scientific research achievements in the fields of pulsars and Fast Radio Bursts (FRB). In the future, there may also be plans to build the FAST Array (FASTA) project, which will build 5 more telescopes similar to the aperture of the FAST in 5 different locations, and its ultra-high sensitivity will be benefited from the length of the baseline. With the upgrade of the project, the receiver system will be further upgraded. We plan to develop a digital backend of Phased Array Feed (PAF) with no less than 330 sampling units on the 1.2 diameter focal plane, the instantaneous bandwidth covers 0.6 to 1.8GHz, the system noise temperature is not higher than 25K, and simultaneous implement the real-time 90*2 digital beamforming.