a. By material: Silicon transistors, Germanium transistors
b. By structure: NPN, PNP. (See Figure 2)
c. By function: Switching transistors, power transistors, Darlington transistors, phototransistors, etc.
d. By power: Low-power transistors, medium-power transistors, high-power transistors
e. By operating frequency: Low-frequency transistors, high-frequency transistors, overclocking transistors
f. By structure and manufacturing process: Alloy transistors, planar transistors
g. By mounting method: Through-hole transistors, surface-mount transistors
Product Parameters
Characteristic Frequency: When f = fT, the transistor completely loses its current amplification function. If the operating frequency is greater than fT, the circuit will not function properly.
fT is called the gain-bandwidth product, i.e., fT = βfo. If the current operating frequency fo and the high-frequency current amplification factor of the transistor are known, the characteristic frequency fT can be obtained. As the operating frequency increases, the amplification factor decreases. fT can also be defined as the frequency when β = 1.
Voltage and Current: This parameter can be used to specify the voltage and current operating range of the transistor.
hFE: Current amplification factor.
VCEO: Collector-emitter reverse breakdown voltage, representing the saturation voltage at critical saturation.
PCM: Maximum permissible power dissipation.
Package: Specifies the physical shape of the transistor. If all other parameters are correct, a different package will prevent the component from being implemented on the circuit board.
