Patent attributes
Systems, methods and apparatus for efficient power control of an RF amplifier for amplification of a constant envelope RF signal are described. A reduction in a size of a pass device of an LDO regulator is obtained by removing the pass device of the LDO regulator from a main current conduction path of the RF amplifier. Power control is provided by varying one or more gate voltages to cascoded transistors of a transistor stack of the RF amplifier according to a power control voltage. Various configurations for controlling the gate voltages are presented by way of a smaller size LDO regulator or by completely removing the LDO regulator. In a case where a supply voltage to the transistor stack varies, such as in a case of a battery, a compensation circuit is used to adjust the power control voltage in view of a variation of the supply voltage, and therefore null a corresponding drift in output power of the RF amplifier.
