LTCC front-end integration for D-band applications (110

Contact :
Alain Péden, Professor
Telecom Bretagne, Lab-STIC UMR 6285
Technopôle Brest-Iroise, CS83818
29238 Brest, Cedex 3
Tfn : +33.(0)
Contact :
Camilla Kärnfelt, Associate Professor
Telecom Bretagne, Lab-STIC UMR 6285
Technopôle Brest-Iroise, CS83818
29238 Brest, Cedex 3
Tfn : +33.(0)
Ph. D. project proposal:
LTCC front-end integration for D-band applications (110-170 GHz)
The applicant has to file his/her candidature before May 10th 2016
The applicant needs a M.Sc. level in electrical or physical engineering with a basic knowledge in
microwave electronics and electromagnetics.
Context and objectives
The objective of this thesis is to realize miniaturized transmit-receive modules (TRX front-ends)
working in the D-band (110-170 GHz) by the use of LTCC (Low Temperature Co-fired ceramics). The
intended applications can be vast, ranging from security solutions (imaging), automotive radars,
radiometry, or a component of the back-haul of future 5G base stations. Thanks to the wavelength’s
small size at these high frequencies (~2 mm for D-band) such a TRX module can be designed to be
light weight and to have a small form-factor, why it could easily be carried by a drone.
The front-end module requires passive and active component’s integration. The active circuits will be
MMICs (Microwave Monolithic Integrated Circuits) which are under development right now with
certain manufacturers. The module could typically include an amplifier, LNA (Low Noise Amplifier) or
MPA (medium power Amplifier), a mixer, a VCO (Voltage Controlled Oscillator) as well as an antenna.
The “in-house” LTCC technological platform that will be used for this project was established in 2009
and continuous improvements have been done throughout Ph.D and research projects ever since.
Today we have a capability to realize LTCC devices close to what can be done at well-known research
institutes such as VTT and IMST.
Planned research activities during the Ph.D. project:
Study of interconnection solutions between the MMIC and the LTCC substrate
Study of interconnection solutions between the LTCC substrate and external components
Thermal control of chips that have a strong dissipation
DC biasing scheme integrated in the TRX module
External requirements
a) To make the interconnection between the MMIC and the LTCC substrate, a good knowledge
of millimeter wave packaging technology must be acquired. A new type of interconnection
transitions have already been proposed by the laboratory, however an important amount of
work remains in order to assure the repeatability and quality up to 170 GHz. This implies
further development of the LTCC fabrication steps as well as a thorough theoretical and
electromagnetic simulation study performed by the Ph.D. student.
b) New solutions to connect the TRX module to other devices are needed. Above 100 GHz,
coaxial connectors are no longer commercially available. Thus an interconnection transition
must be developed in order to connect the TRX module to external waveguide components.
c) Medium Power Amplifiers (MPA) are required for the transmitter part of the front-end. Such
components have a rather limited efficiency and some of the DC power fed to the
component is transformed into heat. We thus need to study and propose thermal control
solutions, such as fluid channels, TIM (Thermal Interface Materials) or thermal vias to
evacuate this heat efficiently.
d) The MMICs need to be fed by DC-bias in order to work correctly. The DC feed network can be
realized in the LTCC structure, on one or several layers. An efficient feed network design
strategy is to be proposed by the Ph.D. student.
e) It is rather common that devices that are produced in research laboratories do not fulfil the
industrial requirements and norms such as environmental requirements (resilience to
temperature variation, humidity, etc.), industrial, military or space qualification (MIL-STD or
JEDEC standard).
Some of our previous publications on LTCC
[1] C. Kärnfelt, « Solutions d’intégration en boîtier de puces MMIC via la technologie LTCC »,
Thèse, Télécom Bretagne/école doctorale SICMA, Brest, France, 2016.
[2] C. Kärnfelt, P. Coant, M. Sinou, J.-P. Coupez, D. Bourreau, et A. Péden, « Grooved Laminated
Waveguides in LTCC for mm-wave packaging », présenté à Micro/Nano-electronics Packaging
and Assembly, Design and manufacturing Forum, (MiNaPAD2015), Grenoble, 2015.
[3] C. Kärnfelt, P. Coant, M. Sinou, J.-P. Coupez, D. Bourreau, et A. Peden, « Grooved Laminated
Waveguide devices for U-, V-, W-and G-band applications », in Microwave Conference
(EuMC), 2015 European, 2015, p. 777–780.
[4] M. Ney et C. Kärnfelt, « Structures de guidage hyperfréquences | Techniques de l’Ingénieur »,
Techniques de l’ingénieur, vol. base documentaire : TIB277DUO. Editions T.I., 2015.
[5] C. Arenas-Buendia, F. Gallée, A. Valero-Nogueira, et C. Person, « LTCC Technology for
Microfluidic Applications Based on the Gap Waveguide Technology », présenté à 20th
European Microelectronics Packaging Conference (EMPC2015), Friedrichshafen, Germany,
2015, p. 1-5.