| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a radio transmission circuit for a mobile communication unit, the number of components of which can be reduced and which is suitable for downsizing. <P>SOLUTION: One PLL synthesizer SS shares functions of a RF frequency band PLL and an IF frequency band PLL among three oscillators for TX, RF, and IF frequency bands having been required for mobile communication units of prior arts, and the required number of the oscillators monopolizing a large area in a chip is decreased to reduce the number of the components. Concretely, the radio transmission circuit is constituted to generate a local oscillation signal used for the RF and IF frequency bands by frequency-dividing an output of a VCO 21 of the RF frequency band PLL. <P>COPYRIGHT: (C)2009,JPO&INPIT |
