The Near Infrared Spectrograph and Photometer (NISP) is one of the instruments on board the EUCLID mission.
The focal plane array (FPA) consists of 16 HAWAII-2RG HgCdTe detectors from Teledyne Imaging Scientific
(TIS), for NIR imaging in three bands (Y, J, H) and slitless spectroscopy in the range 0.9−2µm. Low total noise
measurements (i.e. total noise < 8 electrons) are achieved by operating the detectors in multiple non-destructive
readout mode for the implementation of both the Fowler and Up-The-Ramp (UTR) sampling, which also enables
the detection and removal of cosmic ray events. The large area of the NISP FPA and the limited satellite telemetry
available impose to perform the required data processing on board, during the observations. This requires a well
optimized on-board data processing pipeline, and high-performance control electronics, suited to cope with the
time constraints of the NISP acquisition sequences. This paper describes the architecture of the NISP on-board
electronics, which take charge of several tasks, including the driving of each individual HAWAII-2RG detectors
through their SIDECAR ASICs, the data processing, inclusive of compression and storage, and the instrument
control tasks. We describe the implementation of the processing power needed for the demanding on-board data
reduction. We also describe the basic operational modes that will be managed by the system during the mission,
along with data flow and the Telemetry/TeleCommands flow. This paper reports the NISP on-board electronics
architecture status at the end of the Phase B1, and it is presented on behalf of the Euclid Consortium.