| 摘要 |
PURPOSE:To vary an output level monotonously in response to a change in volume data by providing a maximum attenuation rate of a 2nd attenuator larger than that of a 1st attenuator. CONSTITUTION:An attenuator(ATT) 2 is arranged on a pre-stage and an ATT 1 is arranged as an inter-stage attenuator. An attenuation factor D2 of a 2nd attenuator comes from that of the ATT 1 and since the maximum attenuation of the ATT 1 is larger than that of the ATT 2, the effect of an offset voltage onto an output voltage is reduced when the attenuation is being increased. Furthermore, an operational amplifier whose output reaches a power supply voltage is employed for an operational amplifier of a buffer circuit and a power supply voltage of the operational amplifier is provided to an input voltage VIN. Thus, when the attenuation is being increased, the effect of the offset is reduced. |
