| 摘要 |
PURPOSE:To simplify the constitution of a device and to realize the reduction of cost, miniaturization, and low power consumption, by sharing a high frequency amplifier in two ways by switching two sets of transmission/reception common antennae arranged separately with each other by an antenna switch. CONSTITUTION:When no signal is received, the output of a latch circuit 18 is switched with a switching cycle T decided by the oscillation frequency of an oscillation circuit 19, and the antenna switches 12 and 16 are switched alternately. A wave is transmitted From a communication equipment which transmits a weak wave to either antenna 9 or 10, and when the high frequency amplifier 13 is connected to the antenna 9(or 10), the output 14 of a reception input level detection circuit exceeds a reference value set in advance in a voltage comparator 15. Thereby, the latch circuit 18 is placed under a holding state. And, when transmission is completed, the latching operation of the latch circuit 18 is released, and the latch circuit 18 starts a differential switching operation based on the output of the oscillation circuit 19. |
