The Flipped Voltage Follower: Theory and Applications

The ”flipped voltage follower (FVF)” is an enhanced buffer cell widely employed for low-power and/or low voltage operation. The applications of the FVF and its variations in analog and mixed signal (AMS) circuit design have increased continuously over the last few years. These are specially promising in deep submicrometer CMOS technology. In 2004 the paper ”The Flipped Voltage Follower: A useful cell for low-voltage low-power circuit design” was published [1], where the most important information about this versatile cell was compiled. Since then, several modifications of the FVF and a wide variety of new applications have been reported. No other article with a similar purpose has been published since then. The aim of this chapter is to make a compendium summarizing some of the most relevant information published to date on the FVF. In order to facilitate AMS designers the utilization of this cell in this chapter we revisit, classify and summarize most applications of the basic FVF and its variations. Although it is tutorial in nature, it can be helpful for those who want to introduce themselves in the study of this cell or for experienced designers who want to become familiar with the principle of operation, improved versions and applications, so that both can exploit to its maximum the potential of the FVF in a wide number of applications or also to develop new ones.