HIGH DENSITY COLUMN DRIVERS FOR AN ACTIVE MATRIX DISPLAY

摘要

To reduce the layout area required by LCD column drivers without suffering a significant decrease in performance, a PMOS-based circuit selects a voltage from an upper set of analog display voltages and a NMOS-based circuit selects a voltage from a lower set of analog display voltages. This reduces the layout area by up to roughly a factor of two compared with conventional column drivers which are CMOS-based. Moreover, in a typical dot inversion scheme, where two adjacent columns select voltages from alternating voltage sets, two adjacent columns can share the same PMOS-based and NMOS-based circuits by using multiplexers controlled by a polarity signal to route the digital display data into the sets of switches. This reduces the layout area by up to roughly an additional factor of two.