Patent ID: 8295386

Claim:
A nonlinear filter for inserting, based on an I signal (an in-phase signal) and a Q signal (a quadrature-phase signal) inputted into the nonlinear filter, a pulse into the I signal and the Q signal, and outputting resultant I and Q signals, the nonlinear filter comprising: a determination unit that determines, based on the inputted I and Q signals, whether or not to insert a pulse; a rotation detector that detects, based on the inputted I and Q signals, a rotation direction of variations of the I and Q signals on an IQ plane with respect to the origin on the IQ plane, wherein the rotation direction is represented based on whether the variations of the I and Q signals are in an anticlockwise direction or in a clockwise direction with respect to the origin on the IQ plane; a pulse generator that generates, when the determination unit determines to insert a pulse, a pulse of which at least one of the direction and the magnitude is determined in accordance with at least the detected rotation direction; and an adder that inserts the pulse into the inputted I and Q signals and outputs resultant I and Q signals.