Dirk Stöpel

Ceramic Microwave Circuits for Satellite Communication

KERAMIS is the acronym of a German research and development project funded by the German Space Agency (DLR) and the Federal Ministry of Economics and Technology (BMWI). The consortium is developing an RF circuit technology for Ka band multimedia satellite applications. A set of modules has been designed, manufactured, and tested by the partners of the consortium. The goal of this effort is to qualify the KERAMIS technology for space applications and to participate in an on-orbit-verification (OOV) program of the DLR. The launch of the technology verification satellite (TET) is scheduled for late 2010. This paper will give an overview of innovative circuit and module designs as well as the assembly, integration, and test results of the project. The authors will present a modular circuit concept for state-of-the-art transmitters and receivers in space at around 20 GHz. Selected modules are a 4 × 4 switch matrix, two synthesizers, and other RF modules. All circuits are based on multilayer ceramic (LTCC) incl...

Fine-line structuring of microwave components on LTCC substrates

Low Temperature Co-fired Ceramics (LTCC) are used in a wide range of RF and microwave applications. The ceramic multilayer technology provides a truly three-dimensional circuit technology, hermetical sealing, hybrid integration, and favorable microwave properties at moderate costs. In order to take advantage of high frequencies with guided wavelengths of the order of millimeters, a precision of lines and spaces better than the resolution of 50 µm available with standard patterning methods is crucial.

On-Orbit Verification of a 4×4 switch matrix for space applications based on the low temperature co-fired ceramics technology

Abstract We have developed a compact, high-performance, mechanically robust reconfigurable microwave switch matrix as well as peripheral components such as diode driver, voltage controlled oscillator, and power detector modules for satellite applications using the low temperature co-fired ceramics technology (LTCC) and hybrid integration of integrated circuits. In order to verify the technology for space applications, we combined these components to build a system that enables automated verification of the switch matrix in space, accounting for power consumption, mass, overall geometrical dimensions, and mechanical robustness. The system passed a full space qualification. During a one year On-Orbit-Verification (OOV) mission aboard the German test satellite TET-1 (technology evaluation carrier) launched on July 22, 2012, the correct operation and reliability of the entire switch matrix system and thereby the used technology will be demonstrated.

An industry-level implementation of a compact microwave diode switch matrix for flexible input multiplexing if a geo-stationary satellite payload

We have developed a electronically reconfigurable 4×4 switch matrix for satellite communications at Ka-band downlink frequencies (17 ... 22 GHz), utilizing low-temperature co-fired ceramic multilayer technology. During a successful one-year on-orbit verification aboard a German test satellite, the switch matrix showed continuous reliable operation and achieved the technology-readiness level (TRL = 9) for low-earth orbit missions. Based on these promising results und underlying qualification capabilities, we have designed an advanced version of the switch matrix as part of a flexible input multiplexer for operation during the entire operational lifetime of the German geo-stationary Heinrich-Hertz mission. The challenge of this approach lies in the combination of latest research concepts with an industry-level space-qualified microwave system-in-package approach including an automated hybrid assembly process, following the highest standards for satellite payload systems. Beside introducing and verifying new technologies in orbit, and thus reducing the design cycles for future satellite payloads in general, increased reproducibility and reliability of the module, and reduced manufacturing costs are further important consequences. The switch matrix incorporates double-sided hybrid integration, hermetic sealing of bare-die components, space-qualified PIN-diode switch-ICs, and wire-bonded coaxial connectors.

Efficient Design of Multilayer Microwave Modules using an Element-Wise Simulation Technique

A technique for the fast and efficient modeling of complex microwave modules is investigated. In order to reduce simulation and optimisation time of spatially extended transmission line structures, a library of basic microwave components together with an approach for the decomposition and cascaded simulation of extended microwave circuits is proposed. To verify the design method, simple test structures as well as constituents of challenging low temperature co-fired ceramics (LTCC) modules from an ongoing R& D project are analysed and evaluated. The promising results encourage further efforts to exploit the discussed method for automated design approaches.

High resolution patterning of LTCC based microwave structures for Q/V-band satellite applications

Highly substrate integrated microwave circuits for space applications require a high metal pattern accuracy for transmission line structures and components. Within this work an embedded 60 GHz strip line filter is used as a demonstrator device to compare four fine line structuring processes for multilayer Low Temperature Cofired Ceramics (LTCC). Fine line screen printing (type I), resinate thin film patterning (type II), laser patterning in green state (type III) and laser patterning of fired screen printed thick films (type IV) are compared regarding pattern tolerances, electrical performance and process implementation capability. All substrates were manufactured using a subsequent tape-on-substrate process (ToS) to embed the filter. The filter measurements exhibit an insertion loss of 4 dB at centre frequencies of nearly 60 GHz for all variations.

Microwave crossovers using cascaded couplers for switching applications

The paper describes a passive solution for the implementation of transparent paths within a reconfigurable switch matrix for satellite communications, to improve its availability in case of power failure. The performance of four cascaded identical reduced-length couplers distributed across embedded layers of a ceramic multi-layer substrate has been presented, fulfilling return-loss, isolation and dimensional requirements. The simulated performance parameters will be verified by measurements in due course.

LTCC Based Multi-Electrode Arrays for In-Vitro Cell Culture

Neurobiological concepts based on state-of-the art technology have so far lacked the complexity of actual high-level neurobiological systems. Two key advances are needed to improve our understanding of such systems: in vitro 3D-neuronal cell culture and 3D MEA systems for measuring such 3D-cultures. These requirements call for smart multilayer and packaging technology. The material Green Tape TM from DuPont Nemours is chosen for the presented works, because its compatibility and those of available metallisation with cell cultures is already proven. An LTCC multilayer circuit with gold electrodes is the base of the 3D MEA. The layout of the 3D MEA is designed to fit the MEA2100-System for in vitro recording from Multi Channel Systems and enable thus a comparable data processing to established 2D MEAs Slots. The surface topography of the thick film electrodes and the surface state is investigated with laser scanning microscopy, SEM, XPS and measurements of the wetting angle of contact. The impedance of the ...

Reconfigurable 4 × 4 switch matrix for Ka-band Geo-stationary satellite mission

Abstract A 4 × 4 reconfigurable switch matrix based on low temperature co-fired ceramic technology for Geo-stationary satellite mission at Ka-band downlink frequencies (17–22 GHz) is presented. In comparison to its predecessor, the new generation of switch-matrix features augmented functionality whilst an overall reduced size (40%). The distinguished characteristics include the shifting of matching networks from top-layer into the embedded layers of the multilayer ceramic stack and the elimination of two external peripherals required to digitally control the bipolar current sources of the PIN-diodes based switch integrated circuits. As an additional functionality, four passive transparent paths between corresponding input and output are integrated within the module, to exhibit rudimentary transmission through the module in case of on-board power failure.