| 摘要 |
A protection circuit includes a transformer (11), wherein a terminal (11a) of the transformer (11) is connected to a terminal part (1) of a radio IC, a terminal (11b) thereof is connected to a grounding point, a terminal (11c) thereof is connected to an input or output of an on-chip circuit (7), and a terminal (11d) thereof is connected to a bias power supply circuit (18). A signal is transmitted between a terminal-side inductor (11f) and a circuit-side inductor (11g) due to magnetic coupling therebetween. The terminal-side inductor and the circuit-side inductor are insulated to each other from a standpoint of DC and hence isolated completely to each other. Thus, different voltages can be applied to the terminal part (1) and the input or output of the on-chip circuit (7), respectively. |
