Tiziana Signorelli

670-nA CMOS OTA FOR AMLCD COLUMN DRIVER

A transconductance operational amplifier specifically optimized for a switched-capacitor LCD column driver is presented. It exploits MOS transistors in subthreshold region and dissipates 670 nA at DC. Despite this extremely low quiescent current value, the amplifier exhibits a DC gain of about 80 dB, and a gain-bandwidth product and phase margin around 2 MHz and 70°, with a load capacitance of 500 fF. Besides, working in class AB, the solution provides a slew rate equal to 27 V/μs. With exception of the DC gain, these performances represent an improvement with respect to comparable solutions, and are obtained while halving the area occupation.

Low quiescent current high speed amplifier for LCD column driver

The design of a very low-current transconductance operational amplifier specifically optimized for a switched-capacitor LCD column driver is presented. Despite its stringent standby current requirements (lower than 700 nA), the amplifier exhibits a DC gain of about 80 dB and, working in class AB, provides a slew rate greater than 20 V/mus under a load capacitance of 500 fF. The gain-bandwidth product and phase margin are about 2 MHz and 70deg. With exception of the DC gain, these performances represent a major improvement with respect to comparable solutions, and are obtained while halving the area occupation.