PN Junctions vs Transistors When Building Logic Gates

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SUMMARY

Logic gates are predominantly built using transistors, specifically CMOS technology, rather than PN junctions due to their superior functionality and efficiency. Transistors, such as NPN bipolar transistors, have three contacts, allowing for more complex switching capabilities compared to the two contacts of a PN junction. While both components can act as switches, transistors provide better control over current flow, making them essential for modern digital circuits. The discussion highlights the inherent advantages of transistors in logic gate design, emphasizing their role in enabling advanced electronic applications.

PREREQUISITES
  • Understanding of CMOS technology
  • Knowledge of NPN bipolar transistor operation
  • Familiarity with PN junction characteristics
  • Basic principles of electronic switching
NEXT STEPS
  • Research the design principles of CMOS logic gates
  • Study the operational characteristics of NPN bipolar transistors
  • Explore the differences between PN junctions and transistors in electronic circuits
  • Learn about the applications of transistors in modern digital electronics
USEFUL FOR

Electronics engineers, students studying semiconductor devices, and anyone interested in the design and functionality of logic gates in digital circuits.

Vishera
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Is there any reason why logic gates are built using transistors instead of PN junctions? Wouldn't it be more cost-efficient to use PN junctions? I am referring to CMOS logic gates.

Also, what can a transistor do that a PN junction can't?
 
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Thanks for the post! Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
 
It seems to me that both PN junctions and transistors act as switches. And both switches are voltage-controlled. So what advantage does a transistor have over a PN junction? When the voltage is high on a PN junction, it is in forward bias and it allows current to pass though. When the voltage is low on a PN junction, it is in zero bias and it does not allow current to pass through. When a NPN bipolar transistor's base voltage is high, it allows current to pass through. When a NPN bipolar transistor's base voltage is low, it does not allow current to pass through.

EDIT: Actually, I think I get it now. A PN junction has only two contacts while a transistor has three contacts.
 
I'm glad you realized the problem: transistors are made out of PN junctions!
 

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