A BJT current source is given in the figure. Assume the Si-PNP transistor to operate in the active region. The value of current I in mA is
Right Answer is:
2.15
SOLUTION
For given BJT current source operating in active region
IE = IC + IB
As the value of β is not given we assume that β is very large
Therefore, IB = 0
⇒ I = IE = IC
Applying the KVL loop at the input side through the Zener diode as it regulates the voltage across the emitter resistance.
VZ −IERE − VBE = 0
∵ For PNP transistor potential barrier is −0.7 V
5 − IE × 2 − 0.7 = 0
2 × 103 × IE = 4.3
IE = 2.15 mA
∵ The value of β is not given we assume that β is very large
∴ IE = IC = I = 2.15 mA