| 摘要 |
PROBLEM TO BE SOLVED: To provide a liquid crystal display driver in which low power consumption, high speed operations and stability providing a hardly any oscillating condition are simultaneously satisfied. SOLUTION: Voltages VREF<SB>0</SB>to VREF<SB>(</SB>N<SB>-1)</SB>, which are obtained by resistively voltage dividing the potential between a power supply voltage VDD and a ground potential VSS, are impedance converted by operational amplifiers OP<SB>0</SB>to OP<SB>(</SB>N<SB>-1)</SB>. A switch SWHM is added between the voltage VDD and the output of the operational amplifier OPM. A switch SWLM is added between the potential VSS and the amplifier OPM. The switches SWHM and SWLM are switched by the output signals of comparators COHM and COLM which monitor the output voltages of the operational amplifiers. When the switch SW<SB>0</SB>is switched to the switch SWM, a high speed operation is conducted using the electric supply from the potential VDD or the potential VSS for a sudden change in the output voltage of the amplifier OPM. When the output voltage of the amplifier OPM is not changed (i.e., the switches SW<SB>0</SB>and SWM are not switched), the operations are limited to the amplifier OPM only and therefore, the power consumption is similar to a conventional case and a stable condition for oscillation is realizwed. COPYRIGHT: (C)2004,JPO
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