| 摘要 |
PROBLEM TO BE SOLVED: To provide a bias circuit which suppresses the effect of noise caused by a clock, and also to provide an amplifier circuit utilizing the same. SOLUTION: The bias circuit has: a bias unit which has a transistor and a variable resistor, and generates transconductance in inverse proportion to the variable resistance independently of a power supply voltage in the transistor; a first current source for current mirroring a bias current generated by the bias unit; a reference voltage generating circuit which has first capacitance, second capacitance, a first switch for charging a current of the first current source in the first capacitance, and a second switch for transferring electric charges of the first capacitance to the second capacitance, and generates a reference voltage in the second capacitance; and a control circuit for outputting a control signal which controls a resistance value of the variable resistor so as to conform a voltage of the variable resistor to the reference voltage. COPYRIGHT: (C)2011,JPO&INPIT |
