Advanced pseudo-correlation radiometers for the Planck-LFI instrument

Mennella, A.; Bersanelli, M.; Butler, R. C.; Maino, D.; Mandolesi, N.; Morgante, G.; Valenziano, L.; Villa, F.; Gaier, T.; Seiffert, M.; Levin, S.; Lawrence, C.; Meinhold, P.; Lubin, P.; Tuovinen, J.; Varis, J.; Karttaavi, T.; Hughes, N.; Jukkala, P.; Sjman, P.; Kangaslahti, P.; Roddis, N.; Kettle, D.; Winder, F.; Blackhurst, E.; Davis, R.; Wilkinson, A.; Castelli, C.; Aja, B.; Artal, E.; de la Fuente, L.; Mediavilla, A.; Pascual, J. P.; Gallegos, J.; Martinez-Gonzalez, E.; de Paco, P.; Pradell, L.

Advanced pseudo-correlation radiometers for the Planck-LFI instrument

Authors

Description

The LFI (Low Frequency Instrument) on board the ESA Planck satellite is constituted by an array of radiometric detectors actively cooled at 20 K in the 30-70 GHz frequency range in the focal plane of the Planck telescope. In this paper we present an overview of the LFI instrument, with a particular focus on the radiometer design. The adopted pseudo-correlation scheme uses a software balancing technique (with a tunable parameter called gain modulation factor) which is effective in reducing the radiometer susceptibility to amplifier instabilities also in presence of small non-idealities in the radiometric chain components, provided that the gain modulation factor is estimated with an accuracy of the order of 0.2%. These results have been recently confirmed by experimental laboratory measurements conducted on the LFI prototype radiometers at 30, 70 and 100 GHz.
6 pages, 3 figures