Low-cost, low-mass ltcc down converter for communication satellite payloads

The baseline converter design was conceived at the start to cover all the standard communication bands in C, Ku and Ku+; 5.925 to 6.425 GHz, 12.75 to 14.5 GHz and 17.3 to 18.1 GHz, respectively. The presented EQM unit covers the Ku band. The hybrid Down converter module will normally be integrated with a reference oscillator and DC/DC converter in a common aluminium alloy module. A separate hybrid module front-end using discrete devices optimized for the lowest noise figure can be interfaced to the top of the Down converter module for eventual applications. Depending on the performance requirements, the unit can be easily configured to accept either a TCXO or OCXO, both of ALS design, without the necessity of packaging modifications. For applications, the topmounted WR-62 or WR-75 iso-adaptor, or SMA connectorized isolator (for C band version only) with corresponding LNA hybrid are replaced by a SMA connector flange. The key element for the success of these units is the use of LTCC multi-layer substrate technology which permits high integration and small size. Plus, the development of a complete line of application specific MMIC(s) in Ku band minimizes or totally eliminates post-production tuning which dramatically reduces production lead-time. Macro-hybrid packaging using “chip-and-wire” also eliminates the additional cost of individual packaged parts. This results in considerable overall cost savings when applied to moderate volume production (10 to 50 units typical per program). Dedicated MMIC chip sets covering the various RF and IF bands have been developed to allow easy reconfiguration of the Down converter hybrid without the modification either to the LTCC layout or package. In addition, filtering functions and mixers are realized purposely in microstrip on alumina seperate substrates (and not in the LTCC top layer) are then epoxied; again permitting performance optimization for the various frequency plans. The LTCC hybrid converter is the "heart" of next generation payload equipment for broadband multimedia satellite communication systems, both regenerative and transparent. The use of MMIC devices and advanced packaging technology allows significant reduction of mass and volume mandatory for the realization of large, complex, multi-channel payloads. In fact, the use of LTCC technology in particular has permitted mass of the complete, stand-alone unit including LNA to be reduced to less than 500 grams. This offers very significant improvement when compared to present market, off-theshelf equipment weighing from 700 to 900 grams depending on configuration.