Pulse-modulated polar transmitters for spectrum-efficient wireless applications

The pulse-modulated polar transmitters have been developed to answer the call for the need of linear and efficient power amplification for wireless applications. The envelope of the modulated RF signal is converted into the pulse train by means of pulse width modulation or delta-sigma modulation. The power amplification of the pulse train can be performed by the highly efficient power amplifiers without the constraint of linearity. The modulated RF signal are restored by low-pass or band-pass filtering of the amplified pulse train. With both high linearity and high efficiency, the pulse-modulated polar transmitter is an excellent candidate for spectrum efficient wireless applications.