| 摘要 |
PURPOSE: A transmitting apparatus for portable communication devices is provided to reduce current consumption and increase call time by changing amplification units according to a level output state and to improve linearity and efficiency by amplifying a harmonic component removed signal. CONSTITUTION: The first amplifier(32) is installed between a drive amplifier(10) and an RF SAW(Surface Acoustic Wave) filter(20). A switching part(36) and the second amplifier(34) are installed between the RF SAW filter(20) and an isolator(40) in serial. As the first amplifier(32) has an amplification degree of 16dBm, a signal of 4dBm outputted from the drive amplifier(10) is outputted as a signal of 20dBm through the first amplifier(32). The harmonic components of the signal passed through the first amplifier(32) are removed through the RF SAW filter(20). At this moment, a power of about 2dBm is reduced. The switching part(36) transfers the signal inputted from the first amplifier(32) to two kinds of paths. One(a) of the terminals of the switching part(36) is connected to the input side of the second amplifier(34). The other terminal(b) of the switching part(36) is connected to the output side of the second amplifier(34). Accordingly, the signal outputted through the terminal(a) of the switching part(36) is amplified and outputted through the second amplifier(34), but the signal outputted through the terminal(b) is outputted without being amplified.
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