| 摘要 |
PROBLEM TO BE SOLVED: To cancel an output offset voltage dependent on an offset voltage of a fully differential operational amplifier and relative variations between input resistors and between feedback resistors at a start and a stop.SOLUTION: A positive side variable current source 15p for adding a positive side adjustment signal to a positive side input signal and a negative side variable current source 15n for adding a negative side adjustment signal to a negative side input signal are disposed. The positive side variable current source 15p and the negative side variable current source 15n are controlled such that a phase difference between a positive side PWM modulation signal V3p and a negative side PWM modulation signal V3n becomes zero to implement output offset voltage cancellation. |
