transistor 6

(3) The cut-off frequencies f β and f α are 0.707 times the frequency when β drops to low frequency, which is the cut-off frequency f β of the common emitter; and 0.707 times the frequency when α drops to low frequency, which is the cut-off frequency f α of β and f α of the common base. These are important parameters that indicate the frequency characteristics of the tube, and their relationship is as follows:

ｆβ≈（１－α）ｆα  diode

(4) The characteristic frequency fT decreases as the frequency f increases, and when β decreases to 1, the corresponding fT is an important parameter that comprehensively reflects the high-frequency amplification performance of the transistor.diode

3. Limit parameter

(1) When the collector current Ic increases to a certain value, causing the β value to decrease to 2/3 or 1/2 of the rated value, the maximum allowable current ICM of the collector is called ICM. So when Ic exceeds ICM, although it does not cause damage to the tube, the β value significantly decreases, affecting the amplification quality.diode

(2) When the emitter is open, the reverse breakdown voltage of the collector junction is called BVEBO.

(3) When the collector is open, the reverse breakdown voltage of the emitter junction is called BVEBO.

(4) The collector emitter breakdown voltage BVCEO is the maximum allowable voltage applied between the collector and emitter when the base is open. If Vce>BVCEO during use, the transistor will be broken down.diode

(5) The maximum allowable dissipated power of the collector PCM when the collector current exceeds Ic and the temperature increases, and the parameter changes of the tube due to heating do not exceed the allowable value, is called PCM. The actual dissipated power of the tube is the product of the collector DC voltage and current, i.e. Pc=Uce × Ic. When used, Pc<PCM.diode

PCM is related to heat dissipation conditions, and adding heat sinks can improve PCM.

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