| 摘要 |
PROBLEM TO BE SOLVED: To restrict the degradation in performance of a circuit due to parasitic capacitance and improve a protective function without increasing an occupied area, as well as make it possible for the potential of a terminal portion and the bias potential of an electronic circuit to be cut off without connecting capacitance in series to a signal path.SOLUTION: A transformer 11 is included as a protection circuit, with a terminal 11a, a terminal 11b, a terminal 11c, and a terminal 11d of the transformer 11 connected to a terminal 1 of a radio IC, a ground point, an input or output of an on-chip circuit 7, and a bias power supply circuit 18, respectively. A terminal side inductor 11f and a circuit side inductor 11g have a signal transmitted in between by magnetic coupling and are insulated in DC and completely separated, so that different DC potential can be applied to the terminal part 1 and to the input or output of the on-chip circuit 7. A low frequency signal generated by an electrostatic discharge flows into the ground point connected to the terminal 11b of the transformer 11, and, therefore, its propagation to the on-chip circuit 7 is prevented. |
