| 摘要 |
PROBLEM TO BE SOLVED: To easily suppress an unwanted side wave band and to contrive the increase of prescribed quantity of handling power by using image rejection type frequency converters for an up-converter and a down-converter when a frequency conversion is required. SOLUTION: When an image rejection type frequency converter is used, a 90 deg.-phase device 418 is required. This 90 deg.-phase device 418 is constituted of a digital processing circuit, then I and Q signals are passed through D/A converters 417 and 418, respectively to obtain analog signals, and the signals are inputted to image rejection type up-converters 416 and 426. As for the outputs of the image rejection type up-converters 416 and 426, unwanted waves are eliminated by a filter 419 in common and the output is inputted to a power amplifier 50. Thus, since the image rejection type converter is used, an unwanted side band wave is easily suppressed, and handling power is increased by 3dB, the occurrence of distortion is suppressed. |
