METHOD FOR CONTROLLING ADAPTIVE PRE-DISTORTER LINEAR POWER AMPLIFIER

摘要

PURPOSE: A method for controlling an adaptive pre-distorter linear power amplifier is provided to use a least mean square(LMS) algorithm applying a transversal filtering method, to automatically decide changing amounts of a control signal according to the size of error signals, thereby reducing the number of loop iteration times when a program is performed. CONSTITUTION: The size of an input signal is read, and an optimum control voltage relating to a pre-stored phase and an amplitude is decided as a value nearest to the given input signal. The decided value is set up as an initial control voltage relating to the phase and the amplitude. A frequency of a phase locked loop(PLL) is adjusted to designate a main signal component. The size of the main signal component is read. The frequency of the PLL is adjusted to designate an inter-modulation distortion(IMD) signal component. The size of the IMD signal component is read. A difference between the main signal size and the IMD signal size is decided as a signal difference. The IMD signal size is decided as an error. If the signal difference is bigger than a threshold value, an input signal reading step progresses. If the signal difference is smaller than the threshold value, a variable phase shifter is controlled. A control voltage controlling process relating to the phase shifter is calculated according to algorithms given as given count numbers, and a calculated value is outputted. If control relating to the variable phase shifter is completed, a controlling process relating to a variable attenuator is calculated according to algorithms given as count numbers, and a calculated value is outputted.