Switched mode transmitter architectures

In English With the introduction of new cellular phone standards with increased modulation complexity and signal bandwidth, the design of efficient transmitters will be a major challenge. With this in mind a number of switched mode transmitter architectures are described, both polar and Cartesian ones. The most promising candidates use a combination of supply voltage modulation and other techniques, such as radio frequency pulse width modulation (RF PWM) or polar delta sigma modulation. This takes advantage of the high efficiency of supply voltage modulation combined with the high speed of the other techniques. Since the architectures are polar, however, significant bandwidth expansion occurs, increasing the requirements on the baseband circuits. Also for Cartesian architectures supply voltage modulation can be used to increase the efficiency, for instance in a double LINC architecture.