LFI 30 and 44 GHz receivers Back-End Modules

The 30 and 44 GHz Back End Modules (BEM) for the Planck Low Frequency Instrument are broadband receivers (20% relative bandwidth) working at room temperature. The signals coming from the Front End Module are amplified, band pass filtered and finally converted to DC by a detector diode. Each receiver has two identical branches following the differential scheme of the Planck radiometers. The BEM design is based on MMIC Low Noise Amplifiers using GaAs P-HEMT devices, microstrip filters and Schottky diode detectors. Their manufacturing development has included elegant breadboard prototypes and finally qualification and flight model units. Electrical, mechanical and environmental tests were carried out for the characterization and verification of the manufactured BEMs. A description of the 30 and 44 GHz Back End Modules of Planck-LFI radiometers is given, with details of the tests done to determine their electrical and environmental performances. The electrical performances of the 30 and 44 GHz Back End Modules: frequency response, effective bandwidth, equivalent noise temperature, 1/f noise and linearity are presented

Planck pre-launch status : The Planck mission

Peer reviewe

Frequency and Bandwidth Control of Switchable Microstrip Bandpass Filters using RF-MEMS Ohmic Switches

In this paper a reconfigurable bandpass filter is designed using ohmic-contact cantilever-type Micro Electro Mechanical Systems (MEMS)switches. The filter can switch between two different states with a center frequency tunable range of 13% in C band. The topology allows achieving two accurate center frequencies, each associated with a precisely defined bandwidth, using six MEMS ohmic-switches. The design carefully takes into account the external quality factor for both filter states to ensure a good impedance match at each frequency. The two sets of coupling coefficients and resonator lengths implemented with the MEMS ohmic switches originate the bandwidths and center frequencies required by design specifications. The filter is designed to have center frequencies of 5.5 and 6.2 GHz, with a fractional bandwidth (FBW) of 5 and 3%, respectively. Filter specifications were successfully met with the proposed topology. The filter was fabricated on a quartz substrate and measured responses are in good agreement with simulations

Frequency and Bandwidth Control of Switchable Microstrip Bandpass Filters using RF-MEMS Ohmic Switches

In this paper a reconfigurable bandpass filterisdesigned using ohmic-contact cantilever-type Micro Electro Mechanical Systems (MEMS)switches.The filter canswitch between two different states with a center frequency tunable range of 13% in C band. The topology allows achieving two accurate center frequencies, each associated with a precisely defined bandwidth,using six MEMS ohmic-switches. The design carefully takes into account the external quality factor for both filter states to ensure a good impedance match at each frequency. The two sets of coupling coefficients and resonator lengths implemented with the MEMS ohmic switches originatethe bandwidths and center frequencies required by design specifications. The filter is designed to have center frequencies of 5.5 and 6.2 GHz, with a fractional bandwidth (FBW) of 5 and 3%, respectively. Filter specifications were successfully met with the proposed topology. The filter was fabricated on a quartz substrate and measured responses are in good agreement with simulations