| 摘要 |
PURPOSE:To enable the use of a cheap amplifier and high speed operation and to facilitate the formation of IC by constituting a circuit in which the input offset voltage of an amplifier does not appear in the output as an error. CONSTITUTION:When sampling, switches S11, S12 are closed and a switch S13 is opened by an S/H command signal and amplifiers A11, A12 constitute non- inversion amplifiers of gain 1. When input voltage Vin is applied, a capacitor 11 is charged by the amplifier A11, and the charged Vc at the time of completion of charging becomes VC=VIN-VOS11 where VOS11 is the input offset voltage of the amplifier A11. When holding, switches S11, S12 are opened and the switch S13 is closed by the S/H command signal. Whole loop including amplifiers A11, A12 constitutes non-conversion amplifiers of gain 1, and an equation VOUT=VC+VOS11 holds. By substituting in foregoing equation, VOUT=VIN- V0S11+VOS11=VIN, and the input offset voltage VOS11 is cancelled. |
