| 摘要 |
PROBLEM TO BE SOLVED: To reduce the circuit scale by forming an AGC loop to a pre-stage of an orthogonal modulator in the linearizer circuit so as to eliminate the need for a ROM, an A/D converter and a D/A converter. SOLUTION: A demodulation feedback signal is given to AGC amplifiers 26-1, 26-2 in the case of detecting a phase error, outputs from them are squared by multipliers 27-1, 27-2 and the results are added by an adder 28. An output of the adder 28 is compared with a reference voltage Vref at an adder 29, from which a control voltage for an AGC amplifier is obtained and the voltage is controlled to have an amplitude equivalent to the Vref . Thus, an output of the AGC loop is given to an orthogonal modulator 25 as it is by setting the Vref to be a prescribed level, and a ROM, an A/D converter and a D/A converter having been required for a conventional circuit are not required and the circuit scale is made small. |
