Comparison of conventional and new class AB modifications of the Flipped Voltage Follower and their implementation in high performance amplifiers

Abstract

A comparison between different modifications of the conventional cell denominated as Flipped Voltage Follower to provide class AB operation is presented. Additionally, two new class-AB structures with high linearity and large operational range are introduced, and included in the comparison. Computer simulation shows the operation of these modifications when driving a capacitive load, including the resulting output resistance when the class AB operation is achieved. Also, the implementation of these modifications in a highly linear operational transconductance amplifier is discussed, as well as the impact of the output resistance of these modifications on the linearity of the system. Additionally, a variation of conventional cascoded current mirrors used in the amplifier to achieve very large output currents is presented. Simulation results in 0.5μm technology show the results of the comparison.