| 摘要 |
PURPOSE:To simplify the circuit to reduce the number of parts and improve the spurious characteristic by utilizing the second local oscillation signal having a low frequency to synthesize the first local oscillation signal having a high frequency. CONSTITUTION:In the second local oscillating circuit part 301, the output of a voltage control oscillator 304 is subjected to 1/M1 frequency division in a frequency divider 305 and is inputted as a comparison frequency signal to a phase comparator 305. If the second local oscillation frequency is lower than the output frequency of the voltage control oscillator 304, namely, the operating frequency of the frequency divider 305, the output of the voltage control oscillator 304 has fundamental wave components filtered by a band-pass filter 309 and is supplied to the second mixer 106 and a mixer 312 of the first local oscillating circuit part 302 through an amplifier 310. If the second local oscillation frequency is lower than the operating frequency of the frequency divider 305, the second local oscillation frequency of about 2GHz is synthesized easily when the device is so constituted that 2-fold or 3-fold higher harmonics of the voltage control oscillator 304 are extracted by the band-pass filter 309. |
