Phase Modulating Apparatus, Communication Device, Mobile Wireless Unit, And Phase Modulating Method

摘要

A multimode-based phase modulating apparatus capable of reducing the degradation of modulation precision and suppressing the unnecessary power consumption. The phase modulating apparatus has a switch ( 9 ) for switching the modulation modes of a PLL circuit ( 15 ) between a single-point modulation and a double-point modulation. In a case of a narrow modulation bandwidth such as in a GSM mode, the switch ( 9 ) is turned off to cease a second digital baseband signal (S 2 ), thereby causing the PLL circuit ( 15 ) to perform the single-point modulation in which only a first digital baseband signal (S 1 ) from a frequency division rate generating part ( 10 ) is used for the modulation. Contrarily, in a case of a wide modulation bandwidth such as in a UMTS mode, the switch ( 9 ) is turned on, thereby performing the double-point modulation using both the first digital baseband signal (S 1 ) and the second digital baseband signal (S 2 ).