| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce distortion in an output amplifying circuit of high frequency with a circuit which is small-sized and has small power consumption in a high frequency digital multi-level modulation portable video sound transmitter. <P>SOLUTION: In the digital multi-level modulation portable video sound transmitter of high frequency equal to 2.6 GHz or higher, an intermediate frequency equal to 1 GHz or higher is used. A leading distortion generation circuit for generating an inverse distortion of an output step inversion in the intermediate frequency is provided, a back step of the leading generation circuit is provided with a frequency changing circuit for changing a frequency into one equal to 2.6 GHz or higher, and the front and back of the frequency conversion circuit is provided with a variable gain circuit. The leading distortion generation circuit and the variable gain circuit at the back and front of the frequency changing circuit are controlled so that they are offset between an amount of change in a high frequency output level, at which a distortion generates in the output amplifying circuit of high frequency step, and the distortion, and an amount of change in a high frequency output level, at which an inverse distortion generates in the leading distortion compensation circuit of the intermediate frequency back step, and the inverse distortion. <P>COPYRIGHT: (C)2007,JPO&INPIT |
