| 摘要 |
PROBLEM TO BE SOLVED: To provide a radio transmission circuit for a vehicle that is capable of suppressing harmonic noise while suppressing an increase in a circuit scale, and can be commonly used in a radio transmission system in which transmission frequencies are different from one another, without causing a change of hardware. ! SOLUTION: A rectangular wave drive circuit 5 outputs a rectangular wave drive signal generated on the basis of a transmission carrier clock having a transmission frequency in a radio transmission system 1 for a vehicle. An IV conversion circuit 10 supplies a voltage obtained by amplifying a terminal voltage of a shunt resistor 6 to antenna drive circuits 8a-8c. The antenna drive circuits 8a-8c output sinusoidal wave drive signals on the basis of transmission data Da-Dc and the output voltage of the IV conversion circuit 10. Contact points of selection switches 9a-9c are switched so as to supply either the rectangular wave drive signal or the sinusoidal wave drive signals to ante |
