| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit for cancelling an output offset voltage due to an offset voltage occurring at an input of a fully differential operational amplifier at start-up and at shut-down, while realizing down-sizing of its chip size.SOLUTION: A class D amplifier performs output offset voltage cancellation by adding a voltage on charging/discharging a capacitor C2p from a positive side variable current source 16p to a positive side input signal 5p as a positive side adjustment signal, adding a voltage on charging/discharging a capacitor C2n from a negative side variable current source 16n to a negative side input signal 5n as a negative side adjustment signal, so as to a phase difference between a positive side PWM modulation signal V3p and a negative side PWM modulation signal V3n becomes zero.SELECTED DRAWING: Figure 1 |
