A Class-E GSM-Handset PA with Increased Efficiency

Today´s GSM handset PA implementations give lots of room for efficiency improvement due to the fact that especially in the power-backoff region most of the consumed input power provided by the handset battery is dissipated as heat. This reduces the maximum talking time significantly and makes utilization of smaller batteries impossible. Switching amplifiers provide by default the highest possible efficiency while their drawbacks, such as narrow bandwidth and low linearity, do not apply to the GSM system due to the used modulation scheme, GMSK. In this paper, a demonstrator for GSM handsets is presented. Using Class-E amplification, it provides the necessary output power of 2W at an efficiency far beyond present solutions while maintaining the GSM specifications. Furthermore, concepts for efficient power control of this amplifier are proposed.