System considerations for efficient and linear supply modulated RF transmitters

This paper presents an overview of the envelope tracking RF transmitters which require a dynamic power supply implemented as an envelope modulator. Optimal design of this component requires an understanding of the system and power amplifier (PA) behavior. Here, we specifically address design of transmitters for wireless communications at the base station in the 2.14 GHz band with W-CDMA modulation. PA characterization and a new system modeling method are developed to determine envelope modulator requirements for a given signal type. System measurements of a proof-of-concept ET system dissipates 61% less power than the traditional drive-modulated transmitter.