| 摘要 |
PURPOSE:To prevent a power amplifier from being broken down due to an excessive input by providing a logic circuit, which restricts the Duty ratio of the output of a coincidence detection circuit, at a portable radio equipment, restricting the control voltage of the power amplifier in the portable radio, equipment and setting the upper limit of the output level of the portable radio equipment lower than that at the time of portable use. CONSTITUTION:When a portable radio equipment 1 is connected to a mounted adapter 10, and used for an on-vehicle radio equipment a logic circuit 17 to restrict the Duty ratio of the output of a coincidence detecting circuit 18 is provided. Further, the control voltage of a power amplifier 2 in the portable radio equipment 1 is restricted, and the upper limit of the output level of the portable radio equipment 1 is set lower than that at the time of the portable use. Thus, even when a CPU runs away, and a signal from its software requires the extremely large output level, the excessive input is not applied to the power amplifier 2 used for the mounted adapter 10, and the power amplifier 2 can be prevented from being broken down. |
