| 摘要 |
PURPOSE:To make the modulator small in size and to reduce power consumption by providing a polyphase-shift phase modulator and a polyphase-shift amplitude phase modulator in which phase-shift processing is directly applied to a carrier to be modulated and the circuit scale is reduced while keeping the modulation characteristic. CONSTITUTION:A variable phase-generating device 11 generates a carrier whose phase is shifted synchronously with a base band signal. The carrier is phase- modulated by a phase modulator 17 in response to a base band signal with a roll-off waveform whose roll-off is given via a processing unit 15. That is, since the shift processing of a reference phase of the carrier having been implemented synchronously with the base band signal is implemented by the variable phase generating device 11, the roll-off waveform information to be stored in a memory 13 of the roll-off processing unit 15 is enough to be an information based on a single reference phase. Thus, the storage capacity of the memory 13 is reduced, then the addressing required for accessing the memory is simplified, and the circuit scale and power consumption are reduced. |
