There are two types of transistor based on their materials:
Due to the thinness of the base region and the reverse bias of the collector junction
Figure 2 (b) shows the input characteristic curve of the transistor,
When both the emitter and collector junctions are in a positive bias state in the saturation region,
When the collector is open and a specified reverse voltage is applied between the emitter and base,
The cut-off frequencies f β and f α are 0.707 times the frequency when β drops to low frequencies
