Yamaji Takafumi    Department   SOJO UNIVERSITY  Department of Computer and Information Sciences, FACULTY OF COMPUTER AND INFORMATIONSCIENCES      /(DC)Division of Applied Information Sciences, Graduate School of Engineering      /Division of Applied Information Sciences, Graduate School of Engineering    Position
Country of acquisition	Foreign country (米国)
Patent No.	USP 5,867,777
Date of Grant	1999/02/02
Inventor	Yamaji; Takafumi (Ichikawa, JP), Itakura; Tetsuro (Tokyo, JP), Tsurumi; Hiroshi (Kawasaki, JP)
Patent Title	Variable-gain amplifier circuit, offset control method in variable-gain amplifier circuit, radio receiver with variable-gain amplifier circuit, and radio receiving method in radio receiver with variable-gain amplifier
Details	A variable-gain amplifier circuit has an offset correcting function by which the fluctuation of offset due to the switching of a gain is decreased. In an offset detection mode, an input offset voltage of the variable-gain amplifier circuit is inputted to an offset retaining section, and in a signal amplifying mode, the offset is corrected by subtracting the output of the offset retaining section from an input signal by means of an input section of the variable-gain amplifier circuit. In addition, the variable-gain amplifier circuit can be applied to a radio receiver. The offset produced in a baseband section of a receiver is corrected by the offset correcting function of the variable-gain amplifier circuit, so as to prevent the quality of communication from being deteriorated.