| 摘要 |
PROBLEM TO BE SOLVED: To provide a transmitting device and a portable terminal device for relieving disorder of a transmission output level which tend to occur when switching an amplifier to be used, and for being able to promptly obtain intended power even when a power source voltage is suddenly changed. SOLUTION: For example, an amplification part 17 for high output level performs amplification when the size of a reference voltage level Vref(H) is 2.5 V, and an amplification part 18 for low output level performs amplification when the size of the reference voltage Vref(H) is 2.7V. Therefore, a gain of the switch amplification part 19 can be changed by switching the size of the reference volated Vref(H) between 2.5V and 2.7V. An attenuation amount of an attenuator 30 is determined by the reference voltage Vref(H) and a control voltage Vc(RF). The sum of the gain amount of the switch amplification part 19 and the attenuation amount of the attenuator 30, which are changed when the size of the reference voltage Vref(H) is switched, is approximately zero without adjusting the gain control voltage Vc(RF). COPYRIGHT: (C)2006,JPO&NCIPI
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