The present invention provides a coil structure capable of improving a
differential transmission characteristic by reducing capacitance as much
as possible. A common mode choke coil is constructed so that a section of
each of two coil patterns constructing a thin film coil has an inverted
trapezoid shape which is bilaterally asymmetrical. Because of the
structural characteristic that the section of each of the two coil
patterns has an inverted trapezoid shape which is bilaterally
asymmetrical, the facing area of the two coil patterns contributing to
capacitance is minimized. Thus, the capacitance of the thin film coil can
be reduced as much as possible.