Here I look at the data sheet. There is no indication about the transistors:https://www.fairchildsemi.com/ds/LM/LM324.pdf

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  • \$\begingroup\$ It doesn't matter. The external specs are what matter, regardless of whether they were realized with bipolar transistors, FETs, or magic. Why do you care? In any case, the answer is clearly shown on page 2 of the datasheet you linked to! \$\endgroup\$ – Olin Lathrop Nov 15 '13 at 14:01
  • \$\begingroup\$ im just curious what kind of transistors exist in these little sophisticated ICs. I do really not know why CMOS or TTL preferred to each other. \$\endgroup\$ – user16307 Nov 15 '13 at 14:05
  • \$\begingroup\$ could u copy and paste the line where the transistor type is indicated in 2nd page? i dont know which one is about transistor logic. \$\endgroup\$ – user16307 Nov 15 '13 at 14:07
  • \$\begingroup\$ Its in the schematic, which is clearly showing bipolar transistors. \$\endgroup\$ – Olin Lathrop Nov 15 '13 at 14:09
  • \$\begingroup\$ oh so u interpret it from the way they are drawn. \$\endgroup\$ – user16307 Nov 15 '13 at 14:30

The second page of the data sheet has a very clear schematic that shows the transistors. This amplifier uses bipolar transistors (NPN and PNP) so it is not a CMOS device. Since it is an analog function and not logic, it would be incorrect to say that it is TTL. It is best described as an analog circuit using bipolar transistors.

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  • \$\begingroup\$ could u tell me where is that written the type of transistor logic? \$\endgroup\$ – user16307 Nov 15 '13 at 13:07
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    \$\begingroup\$ There is no logic. This is an analogue integrated circuit. "logic family" has zero meaning \$\endgroup\$ – Scott Seidman Nov 15 '13 at 15:47

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