A Column Driver Architecture With Double Time-Division Multiplexing RDACs for TFT-LCD Applications

This study proposes a thin-film-transistor (TFT) liquid crystal display (LCD) column driver architecture with double time-division multiplexing (TDM) resistor-string digital-to-analog converters (RDACs). A row of sample-and-hold circuits is used as a multiplexer to obtain a high multiplex ratio without requiring low temperature polysilicon TFTs on the display panel. The double TDM operation is proposed to compensate for the kickback noise produced by the output buffer. To improve the linearity of the DAC and the uniformity of the column driver, quasibootstrapped switches are used in the multiplexer to connect the DACs and output buffers. The column driver prototype was implemented by using 0.35 μm/0.5 μm CMOS technology with a worst positive-polarity differential nonlinearity/integral nonlinearity (DNL/INL) of 0.77/0.77 LSB and a negative-polarity DNL/INL of 0.79/0.79 LSB. The average data conversion rate of the RDAC is 18.2 MSPS and the die area per channel is only 0.017 mm
²
.