TRANSMITTER WITH NONLINEARITY CORRECTION CIRCUITS

摘要

In a feedback loop, a modulation carrier signal isamplified or attenuated by a variable gain amplifier (2). A partof a transmission signal amplified by a power amplifier (3) isextracted by a monitor circuit (4), and is detected by anenvelope detector (6). This transmission envelope signal and adistortion-free standard envelope signal produced from astandard envelope generator (7) are compared in an errordetector (8). An error signal obtained by amplifying the errorof the two signals and a DC voltage are added in an adder (9).A gain control terminal (11) of the variable gain amplifier (2)is controlled by using this adder output signal as the controlsignal. The envelope detector (6) is capable of varying theattenuation quantity of the variable high frequency attenuator(61) and the load resistance value of the variable load circuit(63). Therefore, the dynamic range of the transmission monitorcircuit monitor output corresponding to the output voltage ofthe envelope detector in a predetermined range can be expanded.