Question

An npn transistor has a CBJ with an area 120 times that of the EBJ. Find the voltage drop across EBJ and across CBJ when each is forward biased and conducting a current of 2 mA. Also find the forward current each junction when forward biased with 0.6 V.

Answer 1

The voltage drop across the EBJ and CBJ when forward biased with a current of 2 mA can be calculated using their respective areas. The forward current through each junction when biased with 0.6 V can also be determined.

Step-by-step explanation:

In a forward bias configuration, the voltage drop across the emitter-base junction (EBJ) and the collector-base junction (CBJ) can be calculated using the formula:

Voltage drop across EBJ = Voltage drop across EBJ / (Area of CBJ / Area of EBJ) = 0.6 V / (120) = 0.005 V

Voltage drop across CBJ = Voltage drop across EBJ x (Area of CBJ / Area of EBJ) = 0.005 V x 120 = 0.6 V

When the EBJ is forward biased with 0.6 V, the forward current flowing through it can be calculated using the formula:

Forward current through EBJ = 2 mA x (Area of EBJ / Area of CBJ) = 2 mA / (1/120) = 240 mA

The forward current through the CBJ can be calculated as the difference between the total forward current and the forward current through the EBJ:

Forward current through CBJ = Total forward current - Forward current through EBJ = 2 mA - 240 mA = 1760 mA