A local oscillator provides an in-phase local oscillating signal and quadrature-phase signal to first and second mixers outputting an input signal with a mixed in-phase local oscillating signal and quadrature-phase local oscillating signal, respectively. The oscillator comprises a local oscillator having first and second delay cells and outputting said in-phase local oscillating signal and said quadrature-phase local oscillating signal; and a correction circuit for controlling phase matching characteristics, said correction circuit setting bias current flowing in said first and second delay cells of said local oscillator as being to be different. In another embodiment, the phase matching characteristic is controlled by setting the bias voltage applied to the first and second delay cells as being to be different, by setting the width of the active device included in the first and second delay cells dells as being to be different, or by setting impedance of passive device to be different.