Adaptive predistortion linearizer with digital quadrature modem

Linearization of power amplifiers using baseband signal processing is an important technique applied in digital mobile communication equipment. However, the linearizer performance has been severely influenced by IQ gain/phase imbalance and DC offset in quadrature modems, significant elements of linearizers. In order to eliminate these detrimental influences, a linearizer using a digital quadrature modem has been developed. This paper describes an adaptive predistortion linearizer using a simplified digital quadrature modem with which experimental results of less than -63 dBc of ACI (adjacent channel interference) have been obtained. This excellent performance may be applied in base stations relating to mobile communication systems