TABLE OF CONTENTS This chapter introduces the Floating Gate MOS transistor (FGMOS). The properties of this device are described and a simple model for hand analysis is presented. Throughout the chapter, the FGMOS transistor is compared with a standard MOS device, and the main advantages and disadvantages of using an FGMOS instead of an MOS transistor are drawn. Also, some of the common initial problems a designer faces when trying to use the FGMOS are outlined and solutions for them are provided. Hence, in this chapter, the reader will find out how to perform accurate simulations of circuits containing FGMOS devices without having to model them. Also, the frequently asked question how to effectively eliminate the charge accumulated at the floating gate during the fabrication process' is reviewed and answered in one of the sections. Finally, a quantitative analysis of the minimum extra area required by an FGMOS when compared with an MOS with the same channel size is presented in the final sections.
An FGMOS can be fabricated by electrically isolating the gate of a standard MOS transistor, so that there are no resistive connections to its gate. A number of secondary gates or inputs are then deposited above the floating gate (FG) and are electrically isolated from it. These inputs are only capacitively connected to the FG, since the FG is completely surrounded by highly resistive material. So, in terms of its DC operating point, the FG is...
