| 摘要 |
PROBLEM TO BE SOLVED: To provide a voltage-variable gain amplification circuit that has gain linearly and continuously variable with gain control voltage.SOLUTION: A voltage-variable gain amplification circuit 100 includes a first differential amplifier 1, a second differential amplifier 2, a gain control voltage-current conversion circuit 3, and a reference current generation circuit 4. The first differential amplifier 1 and the second differential amplifier 2 are connected in series. The gain control voltage-current conversion circuit 3 converts gain control voltage VC to gain control current IC that varies linearly with the gain control voltage VC. Drain currents Id1 and Id2 of first and second differential input transistors 11 and 12 vary linearly with the gain control current IC. |
