A Rail-to-Rail Class-B Buffer With DC Level-Shifting Current Mirror and Distributed Miller Compensation for LCD Column Drivers

A rail-to-rail class-B buffer with a dc level-shifting current mirror and the proposed distributed Miller compensation is presented for liquid crystal display (LCD) column drivers. By using a dc level-shifting current mirror, the rail-to-rail input stage directly turns on/off the rail-to-rail push-pull output stage without extra comparators. It results in a low-power rail-to-rail class-B buffer. By utilizing the distributed Miller compensation, this class-B buffer achieves the high stability and the fast transient response over a wide-range capacitance load. The class-B buffer is fabricated in a 0.35 μm CMOS process, and its die area is 122 μm × 54 μm. From the experimental results, the measured quiescent current is 3 μA and the settling time for a rail-to-rail full swing to settle within 0.2% of the final voltage for both rising and falling edges is 1.78 μs under a load capacitance of 1200 pF with a power supply of 3.3 V.