| 摘要 |
PROBLEM TO BE SOLVED: To resolve the problem that an output waveform is not made rectangular when a common electrode of a liquid crystal panel is driven with a high frequency without increasing the driving current of an operational amplifier and the problem that the current consumption is increased when the driving current of the operational amplifier is increased. SOLUTION: A first DC voltage V1 and a second DC voltage V2 (V1>V2) are added by an adder 21, and the addition result is outputted as a common voltage VH from an operational amplifier 26 only for rise of the adder 21, and the second DC voltage V2 is outputted as a common voltage VL from an operational amplifier 22 only for fall. For example, a polarity switching signal POL is supplied with a high frequency of 5 kHz or a low frequency of 30 Hz; and when the signal POL is in the high level, a PMOS transistor Qp of a CMOS output circuit 25 is turned on to supply the common voltage VH to a load CL. When the signal POL is in the low level, an NMOS transistor Qn of the CMOS output circuit 25 is turned on to supply the common voltage VL to the load CL from the operational amplifier 22.
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