SIGNAL GENERATING CIRCUIT, FREQUENCY CONVERSION CIRCUIT, FREQUENCY SYNTHESIZER, AND COMMUNICATION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a signal generating circuit capable of generating a sine wave with reduced spurious radiation with a small circuit scale. SOLUTION: The signal generating circuit is characterized in to include: a rectangular wave output circuit 12 for outputting a rectangular wave signal; and a polyphase filter 14 for receiving a signal outputted from the rectangular wave output circuit 12 and associating a pole of its own frequency region with a third harmonic included in the received signal. Thus, the signal generating circuit can obtain the sine wave signal wherein the third harmonic being a most influencing factor of the spurious radiation is reduced with a small circuit area. COPYRIGHT: (C)2007,JPO&INPIT