Projects

Research program on „Silicon carbide MESFET for linear power amplifier design”

Abstract

The aim of the project was to study the potential of silicon carbide technology and respective devices  for the design of power amplifiers for present day digital communication systems. These are: Device suitability for PA design used for multicarrier and digitally modulated signal, accurate large-signal device model accounting for trapping and self-heating effects, device analysis based on the large-signal device model to obtain optimum source and load impedances, PA design including a suitable bias network that has minimal impedance at envelope frequencies.

Funding Agency:        BMBF (German Ministry of Research and Technology)

Research program on „GaN electronics“

Abstract

The aim of the project was the development of a high power measurement techniques for the characterization and modelling of GaN power devices and power amplifiers with special focus on memory effects. A time-domain signal waveform measurement setup for single-/ two- tone stimuli with MTA as receiver has been established. Harmonic tuning up to the fourth harmonic has been realized. Two-tone measurement can be done with envelope source and load pulling in a 50 ohm environment.

Funding Agency:        BMBF (German Ministry of Research and Technology)

Research program on „mobileGaN“

Abstract

The aim of the project is the design of linear high power GaN power amplifiers. UNIK is developing a scalable model for high power devices and is establishing a broadband source-/load pull frequency domain measurement setup (including higher-order zones)  for multi-tone and CDMA  stimuli, usable for device and amplifier characterization, modelling and model verification.

Funding Agency:        BMBF (German Ministry of Research and Technology)

DFG Project “Analysis of IMD Sweet-Spots in Microwave Field-Effect Transistors for Improved Linearity of Power Amplifiers for UMTS Application”.

Abstract

The demand for high linearity of high power amplifiers (HPA) in basestations for UMTS application with a modulation bandwidth of 5 MHz is a great challenge for the circuit design. The situation will become even more challenging in the near future with the introduction of the UMTS LTE and 4G standards with modulation bandwidths of 15 MHz and 100 MHz, respectively. Therefore intensive research activities have been initiated, both in the national and within European research community, to reduce intermodulation distortion (IMD) in a power device. One important point is the right choice of technology (currently Gallium Nitride technology). Furthermore, IMD is also under control of the operating conditions of the transistor. Sweet spots indicate strong slump (desired) in the monotonously increasing IMD characteristic with input power. The proposal is aimed at understanding the occurrence and the control mechanism of sweet spots for the utilization in the HPA design, to improve its linearity.

Funding Agency:         DFG (German Research Community/ Deutsche Forschungsgemeinschaft)

DFG Project “Planare Multichip-Integrationstechnologie für Leistungs-anwendungen im Mikrowellen- und Millimeterwellenbereich“ (Planar Multichip-Integration Technology for Power Application in the Microwave and Millimeterwave Region).

Abstract

This project is a continuation of long term research in the field of quasi-monolithic integration technology (QMIT). Two doctoral theses could already be finished in the HFT department. The current project is performed in cooperation with the technology center of the University of Kassel INA (Institute of Nanostructuring and Analytics). The main goal is the realisation of complete microwave circuits such as power amplifiers to confirm the applicabilility of the QMIT technology to high power applications.

Funding Agency:        DFG (German Research Community/ Deutsche Forschungsgemeinschaft)