With the growth of smart phones, the demand for more broadband, data centric technologies are being driven higher. As mobile operators worldwide plan and deploy 4th generation (4G) networks such as LTE to support the relentless growth in mobile data demand, the need for strategically positioned pico-sized cellular base stations known as ‘pico-cells’ are gaining traction. In addition to having to design a transceiver in a much compact footprint, pico-cells must still face the technical challenges presented by the new 4G systems, such as reduced power consumptions and linear amplification of the signals. The RF power amplifier (PA) that amplifies the output signals of 4G pico-cell systems face challenges to minimize size, achieve high average efficiencies and broader bandwidths while maintaining linearity and operating at higher frequencies. 4G standards as LTE use non-constant envelope modulation techniques with high peak to average ratios. Power amplifiers implemented in such applications are forced to operate at a backed off region from saturation. Therefore, in order to reduce power consumption, a design of a high efficiency PA that can maintain the efficiency for a wider range of radio frequency signals is required. The primary focus of this thesis is to enhance the efficiency of a compact RF amplifier suitable for a 4G pico-cell base station. For this aim, an integrated two way Doherty amplifier design in a compact 10mm x 11.5mm monolithic microwave integrated circuit using GaN device technology is presented. Using non-linear GaN HFETs models, the design achieves high effi-ciencies of over 50% at both back-off and peak power regions without compromising on the stringent linearity requirements of 4G LTE standards. This demonstrates a 17% increase in power added efficiency at 6 dB back off from peak power compared to conventional Class AB amplifier performance. Performance optimization techniques to select between high efficiency and high linearity operation are also presented. Overall, this thesis demonstrates the feasibility of an integrated HFET Doherty amplifier for LTE band 7 which entails the frequencies from 2.62-2.69GHz. The realization of the layout and various issues related to the PA design is discussed and attempted to be solved.

Zugl.: Ulm, Univ., Diss., 2007

Zugl.: Berlin, Techn. Univ., Diss., 2008

With the growth of smart phones, the demand for more broadband, data centric technologies are being driven higher. As mobile operators worldwide plan and deploy 4th generation (4G) networks such as LTE to support the relentless growth in mobile data demand, the need for strategically positioned pico-sized cellular base stations known as ‘pico-cells’ are gaining traction. In addition to having to design a transceiver in a much compact footprint, pico-cells must still face the technical challenges presented by the new 4G systems, such as reduced power consumptions and linear amplification of the signals. The RF power amplifier (PA) that amplifies the output signals of 4G pico-cell systems face challenges to minimize size, achieve high average efficiencies and broader bandwidths while maintaining linearity and operating at higher frequencies. 4G standards as LTE use non-constant envelope modulation techniques with high peak to average ratios. Power amplifiers implemented in such applications are forced to operate at a backed off region from saturation. Therefore, in order to reduce power consumption, a design of a high efficiency PA that can maintain the efficiency for a wider range of radio frequency signals is required. The primary focus of this thesis is to enhance the efficiency of a compact RF amplifier suitable for a 4G pico-cell base station. For this aim, an integrated two way Doherty amplifier design in a compact 10mm x 11.5mm monolithic microwave integrated circuit using GaN device technology is presented. Using non-linear GaN HFETs models, the design achieves high effi-ciencies of over 50% at both back-off and peak power regions without compromising on the stringent linearity requirements of 4G LTE standards. This demonstrates a 17% increase in power added efficiency at 6 dB back off from peak power compared to conventional Class AB amplifier performance. Performance optimization techniques to select between high efficiency and high linearity operation are also presented. Overall, this thesis demonstrates the feasibility of an integrated HFET Doherty amplifier for LTE band 7 which entails the frequencies from 2.62-2.69GHz. The realization of the layout and various issues related to the PA design is discussed and attempted to be solved.

The need for low cost and low size radiometers have encouraged many to look at the implementation of radiometers using MMICs. Compared to their waveguide counterparts, radiometers implemented with MMICs significantly reduce the size and weight of the radiometer, while still maintaining satisfactory electrical performance at millimeter wave frequencies. Utilizing MMICs can also help in significantly lowering the noise temperature of the radiometer, specifically, metamorphic high electron-mobility transistors (mHEMT) have demonstrated very low noise, high gain performance and comparably low cost. This thesis is focused on designing a combined switch and low noise amplifier IC at 36.5 GHz that lowers the radiometer noise temperature while allowing for an accurate calibration. The measured gain from straight and 90 degree input of the switch-LNA, at 36.5 GHz, was 6.6 dB and 7.1 dB, respectively. Likewise, the noise figure of the MMIC was 3.8 dB and 3.3 dB, respectively. The mHEMT implemented SPDT switch has a measured insertion loss, at 36.5 GHz, of 1.3 dB and 0.88 dB with isolation of 25 dB and 36 dB, respectively. The calculated temperature sensitivity based on measured temperature variations was 0.273 K at 36 GHz.

Techn. Univ., Diss--Darmstadt, 2003. / Literaturverz. S. 131 - 136.

This thesis consists of two parts. Part 1 introduces the characteristics of Class E power amplifier. Part 2 is focused on the implementation of Class E power amplifier for 2.4GHz Bluetooth applications. The design procedure follows the theory of class E power amplifier, and is implemented in MMICs and modules. For MMICs, the GaAs HBT foundry services are provided by the GCTC Ltd. and WIN Ltd.. Under single supply voltage of 3.3V and the output power of 20dBm, two designed MMICs have gain 23dB and 11dB, and power added efficiency (PAE) 57% and 72%, respectively. For Hybrid modules, RF transistors are provided by the Filtronic Ltd.. Under the same supply voltage of 3.3V, the measured output power, gain, and power added efficiency are 20 dBm, 25dB, and 75% respectively. Compared with the other types of power amplifiers on the market, Class E power amplifier has higher power added efficiency, and thus can increase the using time of communication system.

Zugl.: Bremen, Univ., Diss., 2005

Zugl.: Erlangen, Nürnberg, Univ., Diss., 2007

University, Diss.--Erlangen-Nürnberg, 2007. / Parallelsacht.: Analyse und Entwurf monolithisch integrierter SiGe Mischerschaltungen für 77 GHz KFZ-Radar.