Patent ID: 7048196

Claim:
A data communication device comprising: a first antenna; a semiconductor circuit for generating signals for use in outputting communication data through the first antenna, the semiconductor circuit having a CMOS configuration of a combination of a P-channel MOS transistor and an N-channel MOS transistor on a single chip; and an antenna connection circuit through which the semiconductor circuit is connected to the first antenna, wherein the semiconductor circuit includes a power-supply-connecting MOS drain output part and a ground-connecting MOS drain output part, said power-supply-connecting MOS drain output part being a drain part of the P-or N-channel MOS transistor connected to a power supply, said ground-connecting MOS drain output part being a drain of the P-or N-channel MOS transistor connected to a ground and wherein the antenna connection circuit has a first diode configured to inhibit a current from flowing into the corresponding semiconductor circuit in the power-supply-connecting MOS drain output part and a second diode configured to inhibit a current from flowing from the semiconductor circuit to the antenna connection circuit in the ground-connecting MOS drain output part.