Patent ID: 7642621

Claim:
A semiconductor device comprising: a well formed in a region where a protection circuit of an input/output terminal is disposed; a plurality of emitter diffusion layers formed on the well and having a conductivity type opposite to the conductivity type of the well; a plurality of first collector diffusion layers formed on the well and having a conductivity type opposite to the conductivity type of the well; a plurality of second collector diffusion layers formed on the well and having a conductivity type opposite to the conductivity type of the well; a base diffusion layer formed on the well and having the same conductivity type as the conductivity type of the well; and an insulating layer isolating the emitter diffusion layers, the first collector diffusion layers, the second collector diffusion layers, and the base diffusion layer, respectively, wherein a first bipolar transistor is composed of the emitter diffusion layers, the first collector diffusion layers, and the base diffusion layer, a second bipolar transistor is composed of the emitter diffusion layers, the second collector diffusion layers, and the base diffusion layer, a third bipolar transistor is composed of the first collector diffusion layers, the second collector diffusion layers, and the base diffusion layer, the emitter diffusion layers are electrically connected to the input/output terminal, first collector diffusion layers are electrically connected to a first power supply terminal, and the second collector diffusion layers and the base diffusion layer are electrically connected to a second power supply terminal.