Question

State the correct reason for neglecting pnp transistor.

(a) Increase in the series collector resistance of pnp transistor

(b) Parasitic capacitance appears between collector and substrate

(c) Current gain of pnp transistor is as low as 1.5 to 30

(d) None of the mentioned

The question was posed to me in examination.

I want to ask this question from Active and Passive Components of IC topic in division IC Fabrication of Linear Integrated Circuits

Answer 1

PNP transistors are neglected in monolithic IC fabrication primarily due to parasitic capacitance effects. The correct answer is (b) Parasitic capacitance appears between collector and substrate. In IC fabrication, the PNP transistor's collector is connected to the substrate, which creates significant parasitic capacitance that degrades circuit performance at high frequencies. This makes NPN transistors preferable for integrated circuit design.