Super Class AB Buffer Amplifier with ICMR and Gain Enhancement for LED Backlight Driver

This paper presents a single stage class AB operational transconductance amplifier (OTA) with input common mode range (ICMR) and gain enhancement as the buffer amplifier for 1:4 time-multiplex liquid crystal display (LCD) panel light-emitting diode (LED) backlight application. The proposed buffer amplifier increases the ICMR to meets the input voltage requirements of the common anode LED driver and the DC gain to improve the accuracy of the current mirror. The design is implemented using the CSMC 0.18um 5V BCDMOS process. The post-layout simulation results show that the proposed buffer amplifier has an ICMR of 0V-4.2V, DC gain of 71.3dB, can drive a 500pF capacitive load with the positive and negative slew rates of 2.56V/us and -6.34V/us, respectively.