Within the framework of this thesis, the work is on the design of reconfigurable multi-standard power amplifiers for GSM/DCS/UMTS in a SiGe BiCMOS7RF technology from STMicroelectronics. The proposed power amplifier is able to adapt dynamically both its linearity and its output power capability, in order to suit the requirements of these standards and input power level in order to maintain optimum PAE and save battery life. GSM and UMTS standards have very different requirements, the most important from the PA design point of view are transmitting frequency, output power and modulation used. Reconfigurable power amplifiers must satisfy the requirements of several standards of communications. UMTS standard uses a QPSK-modulation type: signals have non-constant envelope, which means that the envelope of RF signal varies with time and hence must be preserved in order to keep the full information content of the original message signal. Thus, a good linearity is mandatory in order to avoid envelope distortion. In DCS and GSM standard, a constant envelope GMSK-modulation type is used, so a linear amplification is not mandatory. Moreover, the output power specification requires high output power. In order to reduce power consumption, efforts should be made above all on efficiency. A power amplifier topology is described which is able to modify dynamically important characteristics: class of operation, CP1 and power gain. Optimum efficiency is the aim. All these parameters allow the structure to fulfill the specifications of the standard desired. The realization of a reconfigurable power amplifier led us to validate the proposed methodology functionality. Key words: multi-standard, RF BiCMOS circuits, reconfigurable power amplifier, class of operation, CP1 shifting, linearity-efficiency compromise, optimum efficiency.
