INTERMODULATION DISTORTION IN KAHN-TECHNIQUE TRANSMITTERS

The Kahn Envelope Elimination and Restoration (EER) technique implemen ts a linear RF power amplifier (PA) by combining nonlinear, but effici ent, RF and AF power amplifiers. For signals with high peak-to-average ratios, the average efficiency of a Kahn-technique transmitter can be three to four times that of a transmitter that employs conventional l inear RF PA's. Since switching-mode amplifiers are employed, the linea rity of an EER transmitter depends upon parameters such as the bandwid th of the envelope modulator and the differential delay between envelo pe and phase signals, This paper determines the relationship between t hese parameters and IMD levels and verifies the predictions by laborat ory measurements. The results can be used to determine the requirement s for the components of a Kahn-technique transmitter.