| 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. |
| 主权项 |
1. A protection circuit comprising:
a transformer which includes, between a terminal part of an electronic circuit and an input or output of the electronic circuit, a plurality of inductors magnetically coupled therebetween, wherein one end and the other end of a terminal-side inductor of the transformer are connected to the terminal part and a ground, respectively, the electronic circuit is a circuit of a differential configuration, and a circuit-side inductor of the transformer has a midpoint terminal, one end of the circuit -side inductor is connected to an input or output of one electronic circuit of the differential configuration, the other end of the circuit-side inductor is connected to an input or output of the other electronic circuit of the differential configuration, and the midpoint terminal is connected to a bias power supply circuit of the electronic circuit, wherein the bias power supply circuit generates a desired DC voltage at a bias power supply terminal, and the bias power supply circuit has a transistor having a gate, a source, and a drain, and each of the gate and the drain of the transistor is connected to the bias power supply terminal and the source thereof is grounded. |
