Patent ID: 9143091
Filing Date: 2015-09-22
Classification: H03F,H04L

Abstract:
1. A distortion compensating apparatus comprising: an amplifier that amplifies an input signal and is expressed by a model having a first Linear Time Invariant (LTI) filter that is a linear time-invariant filter for limiting a bandwidth of the input signal, an amplifier circuit that amplifies a signal output from the first LTI filter, and a second LTI filter that is a linear time-invariant filter for limiting a bandwidth of a signal output from the amplifier circuit; a memoryless amplifier unit that acquires a term of each degree from a measurement of the amplitude modulation (AM)-to-AM characteristic and AM-to-phase modulation (PM) characteristic of the amplifier circuit, acquires an estimate of a non-linearity coefficient, and calculates an output from the amplifier when being memoryless for a first input signal based on the estimate; a cross-correlation calculating unit that calculates a correlation between a signal output from the amplifier for the first input signal and an output for the first input signal calculated by the memoryless amplifier unit and calculates an estimate of a transfer function of the first LTI filter and the second LTI filter based on a resultant correlation thus calculated; and a distortion compensating unit that compensates a second input signal based on the estimate of the transfer function calculated by the cross-correlation calculating unit and outputs the second input signal thus compensated to the amplifier.