| 摘要 |
PURPOSE:To obtain a high-precision output without adjustment, by sampling and storing the offset voltage of an operational amplifier and an input voltage in the first period and inverting stored voltages and inputting them to the operational amplifier in the second period. CONSTITUTION:A switch SA is closed, and switches SB and SC are switched to the ground side and the Vout side respectively. If an amplifier A has an offset voltage VOFS, a voltage VIN+VOFS is sampled in a capacitor C. The switch SA is then opened, and switched SB and SC are connected to the + input side of the amplifier A and the ground side respectively. At this time, voltages at both ends of the capacitor C are inverted, and the potential at a point P becomes -(VIN+VOFS), and the output voltage Vout satisfies equation Vout=-(VIN+ VOFS)+VOFS=-VIN. Consequently, the input voltage VIN is inverted tp the Vout side and is outputted. |
