| 摘要 |
PURPOSE:To stably control a transmitter by previously changing a communication signal waveform to transmit to an amplifier in order to compensate the nonlinearity of the amplifier and keeping the balance of a modulator and demodulator. CONSTITUTION:Signals 100-r and 100-theta inputted from input terminals 51 and 52 are transformed 120 into orthogonal coordinates, with the complex signal to which a strain is added in expressed in polar coordinate by a pre-strain addition circuit 110, and D/A converted 130. The amplifier 145 which receives the output controls a gain in order to equalize the mean power of the signals 141-I and 141-Q and transmits the signal 146 to an adder 160. In the adder the signals 141-I and 141-Q are added to be amplified 170 as the complex signals and the output, a part of which is transmitted to the amplifier 245, is outputted from a terminal 53 and the effective value of based signal is calculated in an effective value calculating device 250 so as to control the gain of the amplifier 245 with the signal 251 in proportion to the difference between the mean powers of both signals. And the signal obtained by A/D converting 230 and coordinate converting 220 the output from the amplifier 245, controls the circuit 110. |
