transistor 5

(2) When the collector emitter reverse current Iceo (penetration current) is open at the base (Ib=0), the collector current is determined by applying a specified reverse voltage Vce between the collector and emitter. Iceo is approximately β times that of Icbo, i.e. Iceo=(1+β). Icbo and Iceo are greatly affected by temperature and are important parameters for measuring the thermal stability of tubes. The smaller the value, the more stable the performance. The Iceo of low-power germanium tubes is larger than that of silicon tubes.diode

(3) When the collector is open and a specified reverse voltage is applied between the emitter and base, the current at the emitter is actually the reverse saturation current at the emitter junction.diode

(4) The DC current amplification factor β 1 (or hEF) refers to the ratio of the DC current output by the collector to the DC current input by the base when there is no AC signal input in the common emitter connection, diode that is:

β１＝Ｉｃ／Ｉｂ

2. Communication parameters

(1) The AC current amplification factor β (or hfe) refers to the ratio of the change in collector output current △ Ic to the change in base input current △ Ib in the common emitter connection, diode that is:

β＝△Ｉｃ／△Ｉｂ

The beta of a typical transistor is approximately between 10 and 200. If the beta is too small, the current amplification effect is poor. If the beta is too large, although the current amplification effect is large, diode the performance is often unstable.

(2) The common base AC amplification factor α (or hfb) refers to the ratio of the change in collector output current △ Ic to the change in emitter current △ Ie when connected in a common base configuration, that is:

α＝△Ｉｃ／△Ｉｅ

Because Δ Ic<Δ Ie, therefore α<1.diode  If the alpha value of the high-frequency transistor is greater than 0.90, it can be used

The relationship between alpha and beta:

α＝β／（１＋β）

β＝α／（１－α）≈１／（１－α）