| 摘要 |
PURPOSE:To prevent spurious radiation and to provide a broad band characteris tic for a quadruple phase orthogonal modulator by extracting the carriers of P and Q side data respectively and controlling a voltage controlled oscillator in response to the phase difference between these carriers. CONSTITUTION:The carriers of the P and Q side data are extracted from circuits 8, 9, and they are inputted to a phase comparator 16 through doublers 10, 11, band pass filters 12, 13 and 1/2 dividers 14, 15. Then a phase error output of a comparator 16 is fed to a voltage controlled oscillator 18 via a filter 17. In this case, when a PLL loop comprising the circuits 6, 9, 11, 13, 15, 16, 17 and 18 is in the lock state, each input phase of a phase comparator 16 keeps a phase difference of 90 deg.. Then the circuits 8-15 have a broad band characteris tic and no spurious wave exists. |
