![]() But the transistor is operated (mostly) in the standard way in that source-drain current is monitored and it is controlled by the control gate voltage. The floating gate is an isolated conducting island: it is surrounded on all sides by oxide insulator. ![]() ![]() The original gate (topmost) is now called the control gate. The only difference with the standard MOSFET is the addition of a new gate, called the floating gate, between the original gate and the channel. To the right is a schematic image of a MOSFET floating gate transistor. This is where the floating gate transistor comes in!įloating gate transistor Floating gate transistor schematic (from ) Therefore, as such, the MOSFET can not be used to store information permanently (or semipermanently) without continuous power. If the gate voltage is removed, the transistor forgets that it was applied. Most critically, the MOSFET device is volatile: it forgets its state if power is removed and the gate voltage is not maintained. Physically, the electric field created by the gate repels or attracts the conducting charges in the channel: hence the “field-effect” part of the MOSFET name. make it conduct well or poorly an thus make for a large or small current from source to drain). By changing the voltage on the gate, one can change the conductivity of the channel and thus turn the transistor on or off (i.e. But how much current flows is controlled by the voltage one applies to the gate. In brief, the current flows between the source and drain through the channel. You can see a schematic in the figure on the right. You should read the long section on MOSFET transistors to fully appreciate how the normal transistor works. This is the physical basis for representing information (1 or 0) with flash memory. Since the conductivity can be assessed by putting a voltage across the transistor and seeing how much current goes through it as a result (Ohm’s law), this means the presence or absence of electrons on the floating gate can be determined. Before we get into the details, this means that the information is stored in electrical form: the presence or absence of electrons on a certain part of the transistor (the floating gate) change its conducting properties. Flash memory systems store information as one and zeros on arrays of floating gate transistors.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |