logoalt Hacker News

chasil01/21/20251 replyview on HN

What areas still use bipolar? Does a switching power supply use substantial bipolar? Does anybody still implement TTL or ECL?

Quoting you below...

"The most unusual circuit is the BiCMOS driver. By adding a few extra processing steps to the regular CMOS manufacturing process, bipolar (NPN and PNP) transistors can be created. The Pentium extensively used BiCMOS circuits since they reduced signal delays by up to 35%. Intel also used BiCMOS for the Pentium Pro, Pentium II, Pentium III, and Xeon processors. However, as chip voltages dropped, the benefit from bipolar transistors dropped too and BiCMOS was eventually abandoned."

I didn't realize that BiCMOS lasted so long. I thought it was only used on the original Pentium, but I really didn't look hard.

Edit: BiCMOS has a wiki.

https://en.wikipedia.org/wiki/BiCMOS


Replies

RicoElectrico01/21/2025

I think the best keyword to seek is BCD (Bipolar, CMOS, DMOS) which is a process pioneered by ST. It is quite alive indeed.

Bipolar has for example lower noise than CMOS when it comes to opamps.

show 1 reply