Application of the SiMs SiGe PLL in a 20 GHz Synthesizer Payload Module of the German Keramis Program
Lenz, R.¹; Heyer, H.V.¹; Kulke, R.²; Schwanke, D.³; Voigt, S.^4
1Kayser-Threde GmbH; ²IMST GmbH; ³Micro Systems Engineering GmbH; ⁴DLR

KERAMIS is an industrial-academic R&D consortium consisting of various research institutes and companies specialized in the design, support and fabrication of ceramic microwave circuits for satellites. Our compact, customized modules use multilayer LTCC (low temperature cofired ceramics) for communications at Ka-band frequencies. The Keramis program was started as an expertise in creating precision components which are rugged enough for space and yield a balance between affordable fabrication and high performance microwave applications. The proof of space-worthiness onboard a test satellite will be delivered. The testing program will be fully operational within a short period of time.

A Ka-band synthesizer payload module consisting of a phase locked loop MMIC (PLL-MMIC) and an external voltage controlled oscillator (VCO) was designed which will be used for in-orbit technology verification. The prototype has modular LTCC components in hermetically sealed housings. Standard LGA (land grid array) or wire bond transitions are applied for RF transitions. The LTCC components are mounted on a multilayer PTFE (polytetrafluoroethene) substrate. The heart of the module is a one chip SiGe fractional-N synthesizer in BiCMOS and CMOS with an external VCO (voltage controlled oscillator) at 17 GHz. These MMICs were developed within the ESA-funded SiMs project.

Additional components are hybrids and MMIC amplifiers, mixers, SPDT (single pole double through) switch and a bandpass filter. The modular structure is the key to flexible, low cost designs for transceiver units in multimedia satellite applications. Fabrication and assembly of the layered LTCC substrates is performed by the participating industrial partners.

First test results of the integrated fractional-N synthesizer were promising, yet they also revealed issues which have to be solved. The synthesizer was exposed to stress tests like temperature cycling, extensive vibration testing, pyroshock and thermal vacuum balancing. The results will be presented in the paper in more detail.