| 摘要 |
PROBLEM TO BE SOLVED: To provide a multi-band radio signal transmitter/receiver that can be downsized in its hardware circuit and can reduce the power consumption in spite of adopting a multi-band system. SOLUTION: In the case of a WCDMA(Wideband Code Division Multiple Access) mode, a mixer 42 of a GSM/DCS(Global System for Mobile Communication/Digital Cellular System) orthogonal modulation section 5 provides a signal with 380 MHz resulting from applying 1/2 frequency division to a frequency generated in a fixed PLL loop section 6 without converting the frequency. This signal is given to a frequency divider 8, where it is subjected to 1/2 frequency division, a reference frequency of 190 MHz is obtained and fed to a phase comparator 50 of an offset PLL loop section 9. On the other hand, a mixer 48 of the offset PLL loop section 9 mixes an oscillated signal from a WCDMA VCO 47 with an oscillated signal from a VCO 34 to obtain a signal with a frequency (oscillated frequency by the VCO 34 - oscillated frequency by the VCO 47). An LPF 49 filters this signal and gives the filtered signal to the phase comparator 50 at which the filtered signal is compared with a reference signal with a frequency of 190 MHz. Thus, the oscillated frequency from the VCO 47 in the loop is converged to a frequency (oscillated frequency from the VCO 34-190 MHz). |
