Patent ID: 6337974
Filing Date: 2002-01-08
Classification: H03G,H04W

Abstract:
A cellular mobile telephone terminal comprising a baseband section (101) for processing a voice signal and a radio transceiver section (210) for taking as an input the voice signal processed by said baseband section (101) and for performing communications with a base station, wherein said radio transceiver section (201) comprises a transmitter section (250) for generating a signal for transmission to said base station and a receiver section (220) for receiving a signal transmitted from said base station, said transmitter section (250) comprising an intermediate frequency section (260) for performing heterodyning for modulation and frequency conversion of the voice signal supplied from said baseband section (101) and a radio frequency section (270) for amplifying a radio frequency signal output from said intermediate frequency section (260) and for supplying said amplified signal to an antenna, said radio frequency section (270) comprising a gain controller (271) for controlling the gain of said radio frequency signal output from said intermediate frequency section (260) and a power amplifier (242) for amplifying the power of an output of said gain controller (271), and wherein:said baseband section (101) includes a control section, and said control section detects the output level of said power amplifier (242) while also detecting signal strength of the signal received by said receiver section (220), sets an output level target value for said power amplifier (242) based on the signal strength of said received signal, compares the output level of said power amplifier (242) with said output level target value of said power amplifier (242), and applies to said gain controller (271) a gain control voltage responsive to the result of said comparison, thereby controlling the gain of said gain controller (271) in a feedback loop so that the output level of said power amplifier (242) matches said output level target value of said power amplifier (242); and said gain controller (271) comprises: a signal line (55) containing at least two series variable resistors (51) and (52) and connecting between a signal input part (34) and signal output part (35) for said radio frequency signal; and parallel variable resistors (53) and (54) connected between a groundline (57) and said signal input part (34) and signal output part (35), respectively, wherein said gain controller (271) controls the output of said power amplifier (242) linearly and in substantially continuous fashion by controlling the gain of each of said variable resistors (51), (52), (53), and (54) through said gain control voltage which is applied to a gain control voltage application part (19).