| 摘要 |
PROBLEM TO BE SOLVED: To make an external attaching parts unnecessary, to suppress an influence by an external noise and to suppress an augmentation of mounting space by amplifying a signal of the first channel, amplifying the signal in accordance with reverse characteristics, detecting a condition of balance of both signals, controlling an interest of an amplification circuit and making a circuit of a construction for moving to a balanced condition integrally an integrated circuit. SOLUTION: In an automatic balance operation, a clock selection circuit 12 selects a reference signal CLK1 by a control signal of an automatic balance ON/OFF changeover circuit 4 and supplies the CLK1 to an UP/DOWN counter. When an Lch OUT is bigger than a Rch OUT, a voltage signal of a + polarity is outputted by an L/R balance detection circuit 3 and a counter 11 executes a counting up by the CLK1. Every time a count value becomes large for 1, a gain of a VCA: 1 is lowered for 1dβ and the gain of the VCA: 2 is raised for 1dβ. At the time when a difference of OUT between the Lch and the Rch becomes O and is balanced, a counting operation is stopped. Accompanying to an integration, the number of pin can also be reduced. |
