| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a modulation/amplification circuit which can modulate/amplify a signal suitable for a digital modulation signal with high efficiency. <P>SOLUTION: The modulation/amplification circuit comprises a 180° phase shift circuit 12 generating two carrier signals having a phase difference of 180°, two amplifiers 13 for amplifying the carrier signals, a hybrid circuit 15 for compounding the output from the amplifiers 13, and a modulation circuit for superposing a modulation signal of positive polarity on one of two amplifiers 13 and superposing a modulation signal of negative polarity on the other of two amplifiers 13. Two sets of modulation/amplification circuit may be provided, and a 90° phase shifter 11 and a second hybrid circuit 16 for compounding the output from two sets of modulation/amplification circuit may be provided. Since each amplifier performs amplitude modulation by collector modulation, a class C amplifier can be used and power efficiency can be enhanced to 10-30% from conventional efficiency of 1-10%. PSK, QAM and other OFDM can also be dealt with. <P>COPYRIGHT: (C)2007,JPO&INPIT |
