Torben Baras

Manufacturing Reliability of LTCC Millimeter-Wave Passive Components

The manufacturing reliability of low-temperature co-fired ceramic circuits up to millimeter-wave frequencies and the associated tolerances are studied. The printing accuracy and software tools are initially verified. In the main part of this study, representative circuit elements are analyzed, i.e., a planar bandpass filter, buried filter, and vertical low-pass network, which take advantage of fine line printing and high-permittivity inclusions. The passive structures are investigated for deviations in the magnitude and phase of their scattering parameters, also analyzing temperature effects. A dispersion characteristic is introduced to the simulations in order to achieve the best match with measurements. All samples show very little manufacturing variations up to 67 GHz and a high reproducibility from run to run.

Design and manufacturing reliability of passive components for LTCC millimeterwave hybrid circuits

The design reliability of LTCC circuits up to millimeter wave frequencies and the tolerances associated with the manufacturing process are studied. Representative circuit elements are analyzed, i.e. a planar bandpass filter, a buried DC-block filter and a vertical DC-feed network, which take advantage of fine line printing and high permittivity layer inclusions. In order to distinguish between manufacturing tolerances and variations occurring during the measurement, a reference sample method is introduced. All samples show good to excellent agreement with simulations as well as very little manufacturing variations up to 40 GHz.

Integrated LTCC Synthesizer and Signal Converter Modules at

We report on fully integrated K -band synthesizer and signal converter modules. The designs are realized in low-temperature co-fired ceramics, making extensively use of the multilayer features and advanced capabilities of this substrate system. The interior packaging technology exclusively utilizes flip-chip mounting of bare semiconductors. As a key element a low phase noise synthesizer is integrated in a hermetic surface mount package of 8.7 mm times 15.8 mm, achieving an output power of more than 6 dBm in a range between 19.58-20.2 GHz. The stabilization is achieved by a fractional-N phase-locked loop, all required components being integrated inside and on top of the package. The synthesizer design is extended to dual-sideband and single-sideband converters by including mixers and couplers in the same package.

K

A fully integrated K-band voltage controlled oscillator module is presented. The design is realized in low temperature co-fired ceramics, making extensively use of the multilayer features and advanced capabilities of this substrate system. The interior packaging technology exclusively utilizes flip-chip mounting of bare semiconductors. As a key element, a varactor-tuned substrate-integrated-waveguide resonator and the associated design constraints are presented. The hybrid oscillator is integrated in a hermetic surface mount package of 8mmx 12.5mm, achieving an output power of more than 6 dBm in a tuning range between 19.58GHz – 20.2GHz. The measured phase noise is −118 dBc/Hz at 1MHz offset, a figure-of-merit of −184.7 dB for this design.

-Band

A novel, vertical filter structure for millimeter wave LTCC circuits is presented. The design is based on a circular shielded plate arrangement with embedded inductor loops. Finite element simulations are consulted in order to study the filter response depending on various geometric parameters. Measurements on 8-layer LTCC test vehicles confirm the software predicted performance for frequencies up to 35 GHz

Vertically integrated voltage-controlled oscillator in LTCC at K-Band

A subsystem implementation study of a fractional-N frequency synthesizer for K-band satellite communications is presented. The architecture is based on a subharmonic frequency generation implemented with commercially available voltage-controlled oscillator, phase-locked loop chip and a custom designed frequency tripler implemented in low temperature cofired ceramics with vertical integration techniques. As a key component, the frequency multiplier is analyzed in terms of conversion efficiency and suppression of undesired harmonic signals. With the entire subsystem, a reference-stabilized signal in the range of 19...21 GHz with phase noise of -80dBc/Hz at 10 kHz offset and a 25 kHz channel spacing is achieved. The output power is -1 dBm and the spectral purity better than 25 dBc over the entire range. With the presented approach it is demonstrated that the employed technology can be used to successfully design customized, packaged modules and subsystems in the upper microwave frequency range.

Compact Vertical Bias Networks for LTCC Millimeter Wave Circuits

The on-orbit verification of a double flip-chip packaging concept using low temperature co-fired ceramic (LTCC) technology is presented. Modules based on this concept were designed, fabricated, and assembled as a transparent transponder system. This system is an experimental payload on a small scientific satellite which was launched on July 22, 2012. The transponder uses S-band signaling for the up- and downlink and internally converts the signal to the K-band. The K-band stage employs multiple redundant LTCC modules to improve robustness against failure. The success of the mission is demonstrated by the presented results of a live communication link between the ground station and the experimental payload. This demonstrates technology readiness of the LTCC modules and the underlying packaging concept.

K-Band Frequency Synthesizer with Subharmonic Signal Generation and LTCC Frequency Tripler

A low loss 3/spl times/3-way phase combiner for power amplifier load balancing in 3-sector wireless network cells is presented. Based on an air-filled coaxial double ring structure this design combines very low insertion loss with compact physical profile. Exemplary, the concept is studied for the PCS (personal communication service) transmit band from 1.91 GHz to 1.99 GHz by simulations. Measurements validate the predicted very low insertion loss of 0.05 dB, while return loss and port isolation are both better than 25 dB.

On-orbit verification of an LTCC double flip-chip packaging concept in an S-/K-band satellite transponder

An environmental qualification of a hybrid technology for satellite applications is presented. It is based on low temperature cofired ceramics modules attached in a surface mount technology to a mother board on an aluminum base plate. For the module assembly flip-chip mounting using ultrasonic and thermocompression bonding is considered. As a validation the circuits are exposed to numerous mechanical and thermal testing procedures. In two qualification steps the different manufacturing methods are evaluated and discussed.

3-way low loss phase combiner for power amplifier sharing in 3-sector cellular networks

In this paper two transmission line architectures for intra-layer transitions in multilayer printed circuit boards (PCBs) are presented. Based on a balanced power divider and combiner concept, these can significantly improve the broadband transmission behavior for transmission rates beyond 10GB/s. The electrical performance for state-of-the-art PCBs is reviewed, and compared to the approach by means of simulations and measurements.