| 摘要 |
The invention realizes a power source circuit for a high frequency power amplifying circuit, which achieves excellent responsiveness of output voltage, can be used for a portable telephone of the GSM or WCDMA and a portable telephone capable of performing communications in two or more communication systems such as the GSM and CDMA and, moreover, has high power efficiency. A power source circuit for a high frequency power amplifying circuit is constructed by using both a first direct current power source circuit such as a series regulator whose power efficiency is not high but which becomes the high level quickly, and a second direct current power source circuit such as a switching regulator, which does not become the high level quickly but whose power efficiency is high. When the power source voltage has to become the high level at high speed, both of the series regulator and the switching regulator are simultaneously operated. When the output power source voltage reaches a predetermined level, the operation of the series regulator is stopped.
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