PAE Enhancement Methodology for SiGe Power Amplifier in UMTS/W-CDMA Systems

This paper demonstrates an integrated two-stage 1.95 GHz UMTS/W-CDMA handset RF reconfigurable power amplifier (PA) implemented in a 0.25μm SiGe BiCMOS technology from ST Microelectronics. By acting on bias circuits, a dynamic control of 1 dB compression point (CP1) and power gain of the structure is realized, according to input signal level. Thus, the power added efficiency (PAE) is improved at low level. At low level, the linear gain is 24 dB and the output CP1 is 26.2 dBm. In order to fulfil requirements, especially on linearity, the output power is 24 dBm in a linear class of operation, with a 32.4% PAE. For lower levels, PAE is improved. A chip has been developed to validate the proposed method