Question

Why is the Darlington configuration not suitable for more than two transistors?

(a) Because leakage current increases and voltage gain decreases with multiple numbers of transistors

(b) Because leakage current decreases and voltage gain increases with multiple numbers of transistors

(c) Because leakage current as well as voltage gain increases with multiple numbers of transistors

(d) Because leakage current as well as voltage gain decreases with multiple numbers of transistors

I got this question during an interview.

I want to ask this question from Comparison of Transistor Amplifier topic in section Small-Signal Low-Frequency AC models of Transistors of Electronic Devices & Circuits

Answer 1

Right option is (a) Because leakage current increases and voltage gain decreases with multiple numbers of transistors

The explanation: As the number of transistors increases, the leakage current also increases. The leakage current gets multiplied by the current gain of Darlington configuration.

Generally, the voltage gain of CC configuration is nearly equal to ‘1’ but the voltage gain of Darlington configuration is very less than ‘1’.

Therefore, if we increase the number of transistors in Darlington configuration the voltage gain will ultimately reduce. But, in order to prevent these likely undesirable conditions, Darlington configuration is completely inappropriate for more than two transistors.