1. What are the characteristics of field effect transistors compared with bipolar transistors?

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1. What are the characteristics of field effect transistors compared with bipolar transistors? [Copy link]

answer:

Field effect transistor is another semiconductor amplifier device. In field effect transistor, only majority carriers participate in conduction, so it is called unipolar transistor; while ordinary transistors participate in conduction, both majority carriers and minority carriers participate, so it is called bipolar transistor. Since the concentration of minority carriers is easily affected by temperature, the former is superior to the latter in terms of temperature stability and low noise.

2. Bipolar transistors are current-controlled devices, which control the output current by controlling the base current. Therefore, there is always a certain current in the base, so the input resistance of the transistor is low; field-effect transistors are voltage-controlled devices, and their output current is determined by the voltage between the gate and the source. The gate basically does not take current, so its input resistance is very high, up to 10^9~10^14Ω. High input resistance is a prominent advantage of field-effect transistors.

3. The drain and source of the field effect transistor can be interchanged, and the gate voltage of the depletion-type insulated gate transistor can be positive or negative, which is more flexible than the bipolar transistor.

4 Both field effect tubes and triodes can be used for amplification or as controllable switches. However, field effect tubes can also be used as voltage-controlled resistors, which can work under micro-current and low voltage conditions. And it is easy to integrate. It is widely used in large-scale and ultra-large-scale integrated circuits.