Patent ID: 6310593
Filing Date: 2001-10-30
Classification: G09G

Abstract:
A liquid crystal driving circuit, comprising:a plurality of reference voltage input terminals for inputting a plurality of respective reference voltages;reference voltage selecting means for selecting and outputting a first reference voltage and a second reference voltage from the plurality of reference voltages, using a digital signal of N bits for multi-tone display;a first capacitor and a second capacitor, whose respective first electrodes are connected to each other;a first switch for connecting and disconnecting respective second electrodes of said first capacitor and said second capacitor, which are not connected to each other;a select switch for selecting and applying one of the first reference voltage and the second reference voltage to the second electrode of said first capacitor in accordance with the digital signal;a second switch for connecting and disconnecting the second reference voltage with respect to the respective first electrodes of said first capacitor and said second capacitor;a differential amplifier circuit, whose non-inverted input terminal is connected to the second reference voltage, for outputting from an output terminal an analog signal for multi-tone display that is in accordance with the digital signal;a feedback capacitor, whose one electrode is connected to an inverted input terminal of said differential amplifier circuit;a third switch for connecting and disconnecting an other electrode of said feedback capacitor with respect to the respective first electrodes of said first capacitor and said second capacitor;a fourth switch for connecting and disconnecting the other electrode of said feedback capacitor with respect to the non-inverted input terminal of said differential amplifier circuit;a fifth switch for connecting and disconnecting the output terminal of the differential amplifier circuit with respect to the inverted input terminal thereof; anda sixth switch for connecting and disconnecting the second electrode of said second capacitor with respect to the output terminal of said differential amplifier circuit.