Provided two CORDIC processors, each including: two input ports representing real and imaginary input ports; and two output ports representing real and imaginary output ports; wherein real and imaginary parts of a first input signal are applied to the imaginary input ports of the first and second CORDIC processors; real and imaginary parts of a second input signal are applied to the real input ports of the first and second CORDIC processors; the first and second CORDIC processors rotate the respective input signals applied thereto by 45 degrees in the clockwise direction; respective data from the real output ports of said first and second CORDIC processors constitute real and imaginary parts of a first output signal; and respective data from the imaginary output ports of said first and second CORDIC processors constitute real part and imaginary part of a second output signal.