Question

What is the value of voltage VB of a CB amplifier configuration if VCC = 12V, R1 = 25kΩ and R2 = 6kΩ?

(a) 2.84V

(b) 13.03V

(c) 2.45V

(d) 2.32V

I had been asked this question in an interview for job.

Question is from Simplified Calculations for the CB Configuration topic in division Low Frequency Transistor Amplifier Circuit of Electronic Devices & Circuits

Answer 1

Correct choice is (d) 2.32V

The explanation: The voltage VB of a simplified common base amplifier configuration can be calculated using VB = I × R2. Given, VCC = 12V and R1 = 25kΩ and R2 = 6kΩ:

I = VCC / R1 + R2 = 12 / (25 + 6) = 0.387mA

VB = I × R2 = 0.387mA × 6kΩ = 2.32V