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Circuits de protection et de linéarisation à très basse consommation pour amplificateurs de puissance RF monolithiques à fort rendement et haute linéarité

Walid Karoui 1
1 LAAS-MOST - Équipe Microondes et Opto-microondes pour Systèmes de Télécommunications
LAAS - Laboratoire d'analyse et d'architecture des systèmes
Abstract : The researches carried out in this thesis are related to the design of protection and linearization circuits enabling RF power amplifier modules to meet all the constraints of wireless telephony, namely: ruggedness, linearity, low power consumption, downsizing and cost. In the first part of this memory, we study the improvement of power amplifier ruggedness against impedance mismatches that are induced by environment variations of the handset antenna. The analysis of the failure mechanisms of HBT GaAs and HBT SiGe transistors demonstrates that the current of the final stage has to be limited. Then, we designed an original protection circuit based on the detection of the collector current of the power transistor. The developed protection circuit is very compact and it is monolithically integrated on a power amplifier die. It does alter neither the output power, nor the power added efficiency under a 50 Ohms load. The protected power amplifier passes ruggedness tests with VSWR up to 10 and battery voltages up to 5V. The simplicity and the effectiveness of the current detection circuit has enabled in a second step, the design of a linearization circuit compatible with a monolithic integration in a power amplifier for EDGE and WCDMA standards. The linearization technique, which is based on envelope injection, is implemented using an innovative topology for the detection of the signal envelope. Thanks to the ultra low current consumption of the new linearization circuit, it becomes possible to overcome the linearity/efficiency trade-off usually encountered. This new linearization circuit is implemented into a PA which is integrated in a HBT SiGe technology. The PA linearity is enhanced by 12 dB at the nominal output power
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Submitted on : Tuesday, December 11, 2007 - 11:17:15 AM
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  • HAL Id : tel-00195582, version 1

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Walid Karoui. Circuits de protection et de linéarisation à très basse consommation pour amplificateurs de puissance RF monolithiques à fort rendement et haute linéarité. Micro et nanotechnologies/Microélectronique. Université Paul Sabatier - Toulouse III, 2007. Français. ⟨tel-00195582⟩

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