A 10-bit 1026-Channel Column Driver IC With Partially Segmented Piecewise Linear Digital-to-Analog Converters for UHD TFT-LCDs With One Billion Color Display

Abstract

A 10-bit 1026-channel column driver IC with partially segmented piecewise linear digital-to-analog converters (DACs) was designed, simulated, and prototyped. This device is intended to improve the color depth of ultra-high-definition thin-film transistor liquid-crystal displays. The proposed column driver can output a precise gamma-corrected transfer curve without any loss of effective bit resolution. The overall chip area of the driver IC is minimized by including an area-efficient two-voltage selector, a 2-to-4 decoder embedded level shifter, and a DAC-embedded gm-modulation operational amplifier with linearity-enhanced differential pairs. A maximum inter-chip deviation voltage of output (DVO) of 16 mV was measured from five of the proposed column-driver ICs. The die dimensions of the 1026-channel column driver IC are of only 18.14 mm × 1.2 mm. The maximum settling time of the prototype is 5.6 μs when driving a load with 5-kΩ resistance and 300-pF capacitance within 10-mV tolerance of the final voltage.