What is a MOS tube
The MOS tube is the metal oxide semiconductor field effect transistor, or the metal insulator semiconductor. The source and drain of the MOS tube can be switched, and they are both n-type areas formed in the P-type Backgate. In most cases, the two regions are the same, and the switching of the two ends does not affect the performance of the device. Such devices are considered symmetric.
A bipolar transistor amplifies a small change in the input current and outputs a large change in the output. The gain of a bipolar transistor is defined as the ratio of output to input current (BETA). Another type of transistor, called a field effect tube (FET), converts a change in the input voltage to a change in the output current. The gain of an FET is equal to its Transconductance, defined as the ratio of the change in output current to the change in input voltage. Commonly available in the market are N channel and P channel, please refer to the picture on the right (N channel depletion MOS tube) for details. The common low-voltage MOS tube in P channel.
The fET affects the current flowing through the transistor by projecting an electric field onto an insulating layer. No current actually flows through the insulator, so the GATE current of the FET tube is very small. The most common FET USES a thin layer of silicon dioxide as an insulator under the GATE pole. Such transistors are called metal oxide semiconductor (MOS) transistors, or MosFEts. Because MOS transistors are smaller and use less power, they have replaced bipolar transistors for many applications.
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