Iterative Bandwidth Limitation for High Efficiency EER Power Amplifier

Kahn´s envelope elimination and restoration (EER) architecture can achieve high efficiency and linearity, but suffers from expanded bandwidth of polar drive signals when used with modern modulation schemes such CDMA and orthogonal frequency division multiplexing (OFDM). This paper proposes a new technique which uses iterative bandwidth limitation to reduce the bandwidth expansion of the polar drive signals. The technique reduces bandwidth expansion with the cost of error vector magnitude (EVM) buildup and spectral splatter. The paper also shows that further improvement in bandwidth reduction can be achieved using well known partial transmit sequence (PTS) method to select the signal with the maximum bandwidth limitation and quantifies the EVM for the proposed schemes.