Title: Frequency dividing circuit and multimode radio device using same
Application Number: 200580002965 Application Date: 2005.03.02
Publication Number: 1910826 Publication Date: 2007.02.07
Approval Pub. Date: Granted Pub. Date:
International Classifi-cation: H04B1/40;H03D7/00;H03K21/00;H04B1/26
Applicant(s) Name: Matsushita Electric Ind Co., Ltd. Address:
Inventor(s) Name: Hosokawa Yoshifumi;Saito Noriaki;Matsuo Michiaki;S
Attorney & Agent: qian dayong bo maiwen
Abstract:
    Conventional multimode radio devices have a frequency dividing section of a large circuit scale because as many frequency dividers as the radio systems are required. A frequency dividing section (22) comprises a frequency divider (19) for dividing the frequency of the output of a local oscillator, a frequency divider (20) for dividing the frequency of the in-phase local oscillation signal of the frequency divider (19), and a dummy circuit (21) connected to the output end of the quadrature local oscillation signal of the frequency divider (19). During the operation in a first frequency band, the output of the frequency divider (19) is used for modulation/demodulation; during the operation in a second frequency band, the output of the frequency divider (20) is used for modulation/demodulation. For the first and second frequency bands, the frequency divider (19) is commonly used. However, during the operation in the first frequency band, the phase difference between the in-phase local oscillation signal which is the output of the frequency divider (19) and the quadrature local oscillation signal can be maintained because the dummy circuit is made identical with the input amplifier of the frequency divider (20). As a result, the frequency dividers are commonly used, and the combinatory circuit scale is reduced.
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