1. The field effect transistor is the voltage control element, and the bipolar junction transistor is the current control element. When only a small amount of current is allowed to be taken from the case, the use of the effect tube should be selected; And in the signal voltage is low, and allow to take more current from the signal source condition, should choose bipolar transistor.

2, some of the field effect tube source and drain can be used interchangeably, grid voltage can also be positive or negative, flexibility is better than bipolar transistor.

3, the field effect tube is the use of a majority of carriers to conduct electricity, so it is called a unipolar device, and bipolar junction transistor is a majority of carriers, but also use a few carriers to conduct electricity. So it's called a bipolar device.

4, the field effect tube can work in very small current and very low voltage conditions, and its manufacturing process can be very convenient to integrate many field effect tubes on a silicon chip, so the field effect tube has been widely used in large-scale integrated circuits.