Lecture: Gate Logic with NMOS and CMOS Technology

Introduction

• Gate Logic: Focus on basic gate logic functions using NMOS and CMOS circuitry.
• Compared to Switch Logic discussed previously.

Basic Gate Logic Functions

• Inverter (NOT Gate):
  • Variants: NMOS Inverter, CMOS Inverter, BiCMOS Inverter.
  • CMOS Technology: First basic circuit was the inverter, produces a complementary output by circuit behavior.
• NAND Gate:
  • Extended from inverter logic.
• NOR Gate:
  • Similar extension to create NOR gate logic.

Universal Gates

• NAND and NOR Gates: Fundamental gates producing complemented logic outputs.
• Design of additional gates (AND, OR) from NAND and NOR gates.
• Technologies used: NMOS, CMOS, BiCMOS.

NMOS Logic

• NMOS Transistors: Exclusively uses NMOS transistors.
  • Variants: Depletion Mode & Enhancement Mode.
• Depletion Mode Transistor: Acts as an 'on' transistor by default.

CMOS Logic

• CMOS Structure: Combination of PMOS and NMOS transistors.
  • PMOS in pull-up, NMOS in pull-down.
• Substrate Terminal: Connected to the source; affects threshold voltage.

BiCMOS Logic

• BiCMOS Technology: Combination of Bipolar and CMOS technologies.
  • Uses NPN/PNP transistors along with PMOS and NMOS transistors.
  • Push-pull configuration: For efficient switching.

Designing Basic Circuits

Inverter Circuits

• NMOS Inverter:
  • Comprises depletion and enhancement mode transistors.
• CMOS Inverter:
  • PMOS in series and NMOS in parallel.
• BiCMOS Inverter:
  • Combines CMOS and bipolar transistors for improved performance.

NAND Gate

• CMOS NAND Gate: Realized by connecting PMOS in parallel and NMOS in series.
  • NMOS Logic: Uses depletion mode transistors in pull-up.
  • BiCMOS NAND: Extends CMOS NAND with bipolar technology.

NOR Gate

• CMOS NOR Gate: Realized by connecting PMOS in series and NMOS in parallel.
  • NMOS Logic: Utilizes depletion mode transistor in pull-up.
  • BiCMOS NOR: Combination of CMOS and bipolar technology.

Summary

• Creation of inverter, NAND, and NOR gates using NMOS, CMOS, and BiCMOS Technologies.
• Introduction to other CMOS Logic Types (dynamic, pseudo-NMOS) to be covered in next video.

Conclusion

• Next Video: Discussing other forms of CMOS logic such as pseudo-NMOS, dynamic logic, etc.