A radiometer back end module based on broadband low noise
amplifiers and band pass filters is presented. Low noise
amplifiers are multistage HEMT MMIC chips. A 20% of
bandwidth at 30 GHz have been achieved. The passband is fixed
by coupled lines microstrip filters. A complete module containing
two identical branches of amplification and filtering stages with a
gain greater than 30 dB has been developed. The low 1/f noise
behavior of gain fluctuations allows the module to be used as the
back end module for the differential radiometers in the european
scientific mission Planck. Details of the MMICs chips and filters
assembly as well as experimental results are included
