| 摘要 |
PURPOSE:To reduce a transmission power loss with relatively simple constitution by providing a phase shifter in a path which includes a phase modulator. CONSTITUTION:For the operation of a two-phase modulator, main switch SW is closed to apply the output signal of switching signal source PSS to phase shifter PS and change-over switch TSW, and the phase shift angle of phase shifter PS is set to 90 deg. to equalize digital signals supplied to two modulators MOD1 and MOD2. Therefore, since output signals of both the modulators are in phase with each other in this case, signals of paths PTH1 and PTH2 are superposed mutually when mixed by the 2nd hybrid circuit HB2 to reach output terminal OUT. Consequently, the power loss is only 3dB in the 1st hybrid circuit HB1 and 3dB less than that of a four-phase modulator. |
