| 摘要 |
PURPOSE: A cellular phone receiver which does not require an intermediate frequency is provided so that power can be sufficiently amplified with stability, by separating an RF amplifier in a time region, instead of a frequency region. CONSTITUTION: A band-pass filter(90) selects an RF frequency band signal among input signals from an antenna, and outputs the selected signal to the first RF amplifier(100). In order to compensate for power loss, the first RF amplifier(100) amplifies the RF signal from the band-pass filter(90), and outputs the amplified signal to a delay line(110). Here, the delay line(110) receives the signal from the first RF amplifier(100), and outputs the delayed signal to the second RF amplifier(120), thereby separating the RF amplifier in the time region. Accordingly, so long as the delay line(110) is not selected short, an instable frequency is a low frequency far from the RF frequency region, thus overcoming instability. In addition, the second RF amplifier(120) re-amplifies the signal from the delay line(110), and outputs the amplified signal to a demodulator(130). The demodulator(130) converts the analog signal from the second RF amplifier(120) into a digital signal, and processes the digital signal to obtain a wanted baseband signal. As a result, power can be sufficiently amplified with stability.
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