	US 7,567,610 B2
	Frequency conversion circuit, radio frequency wave receiver, and radio frequency transceiver
Alberto O. Adan, Ikoma (Japan); and Shinji Kamiya, Kyoto (Japan)
Assigned to Sharp Kabushiki Kaisha, Osaka (Japan)
Filed on Oct. 29, 2004, as Appl. No. 10/976,500.
Claims priority of application No. 2003-372535 (JP), filed on Oct. 31, 2003.
Prior Publication US 2005/0117664 A1, Jun. 02, 2005
Int. Cl. H04B 1/38 (2006.01)

U.S. Cl. 375—219 [455/73]

4 Claims

1. A radio frequency transceiver, comprising:

a radio frequency receiver for receiving a radio frequency carrier wave having a desired frequency; and

a radio frequency transmitter for transmitting a carrier wave having a radio frequency,

said radio frequency receiver, including:

a frequency conversion circuit for downconverting a radio frequency signal having a desired frequency into two based-band signals having different phases,

said frequency conversion circuit, including:

a first mixer for mixing the radio frequency signal with a first oscillation signal so that the radio frequency signal is downconverted into an intermediate frequency signal; and

a second mixer for mixing the intermediate frequency signal received from the first mixer with two second local oscillation signals having different phases, respectively, so that the intermediate frequency signal is downconverted into the two base-band signals,

the two local oscillation signals having phases of 0° and 270°, respectively, and

f_LO1=k×f_RF, f_LO2=f_LO1/m, and k=m/(m−1) being satisfied, where f_RFindicates a frequency of the radio frequency signal, f_LO1indicates a frequency of the first local oscillation signal, f_LO2indicates a frequency of the second local oscillation signal, k indicates an arbitrary number satisfying k>1, and m indicates an arbitrary number satisfying m>1,

said radio frequency transmitter, including:

a quadrature modulator for upconverting the base-bands signals directly into a radio frequency signal having the frequency f_RF,

the quadrature modulator, including:

third mixer for mixing an in-phase component of the base-band signal with a clock signal having the frequency f_RFand a phase of 0°; and

a fourth mixer for mixing a quadrature component of the base-band signal with a clock signal having the frequency f_RFand a phase of 90°,

said radio frequency transceiver, including a signal generator comprising:

an oscillator for generating the first local oscillation signal;

a divider for dividing the frequency of the first local oscillation signal into 1/m so as to generate the second local oscillation signals having phases 0° and 270°, respectively;

a fifth mixer for the first local oscillation signal generated by the oscillator with the second local oscillation signal, having the phase of 0°, generated by the divider so as to generate the clock signal having the frequency f_RFand a phase of 0°, and

a sixth mixer for mixing the first local oscillation signal generated by the oscillator with the second local oscillation signal, having the phase of 270°, generated by the divider so as to generate the clock signal having the frequency f_RFand a phase of 90°.