INPUT LEVEL DETECTION TYPE AMPLIFIER CIRCUIT

摘要

PROBLEM TO BE SOLVED: To provide an input level detection type amplifier circuit capable of keeping the detection precision of an input signal level highly precisely independently of temperature even if there is variation of a temperature characteristic in a variable gain amplifier circuit and a detector. SOLUTION: One signal that is amplified by the variable gain amplifier circuit 3 and distributed by a distributer 4 is outputted from an output terminal 5, and the other signal is detected by the detector 6 and inputted to a gain adjusting part 9. A detection signal compensating part 29 of the gain adjusting part 9 outputs a target value of a detection signal from temperature information and detection voltage in reference temperature, and a detection signal subtracting part 24 subtracts the detection signal from the target value. A control part 14 controls a gain control signal so as to make a subtraction result small. A gain control signal compensation value generating part 16 outputs a gain control signal compensation value from the temperature information and the gain control signal at the reference temperature, and a gain control signal compensating part 13 compensates the gain control signal on the basis of the gain control signal and a gain control signal compensation value. An input level signal generating pat 20 outputs an input level signal corresponding to the gain control signal. COPYRIGHT: (C)2004,JPO