| 摘要 |
PURPOSE:To improve remarkably the S/N of a power supply by increasing the capacitance of only required part among capacitors constituting a switched capacitor filter. CONSTITUTION:Since a noise signal N<5> of an operational amplifier OPA5 is increased further because of a positive feedback loop in which the signal is fed back via a feedback capacitor C30 of an operational amplifier OPA3, the S/N of a power supply is deteriorated. It is required to suppress a noise signal N3 generated in the operational amplifier OPA3 to improve the deterioration. Then, an integration capacitor CH3 connected between an input and an output of the operational amplifier OPA3 is increased. Further, a noise signal inputted to the operational amplifier OPA3 is suppressed at the same time. Thus, it is required to suppress a noise signal N1 generated in the operational amplifier OP1 and then to increase an integrating capacitor CH1. |
