In BJT there as two configuration 

1. NPN BJT

2. PNP BJT

1. NPN  BJT:

2. PNP BJT:

• Ie=Ic +Ib

• Ic=𝜷Ib

• 𝞪=𝜷/1+𝜷 

• Ic= 𝞪Ie 

• 𝞫=𝝰/1-𝝰

Region of operation of BJT for NPN transistor: 

• active region 

• saturation region 

• cut off region

1. Active Region:

In active region emitter base junction is forward biased and collector base junction is reverse biased 

2. Saturation region:

In saturation region both emmeter base and collector base are in forward biased. 

3. Cut off region 

In this region both the collector base and emitter base are in reverse biased condition.