Explain CMOS technology basics

 o   CMOS stands for Complementary Metal-Oxide-Semiconductor. It's the dominant technology for constructing integrated circuits.

o   Complementary: It uses both NMOS (N-channel Metal-Oxide-Semiconductor) and PMOS (P-channel Metal-Oxide-Semiconductor) transistors, typically paired together.

o   Structure:

    o   NMOS: Conducts current (electrons) when its gate voltage is high (logic '1').  Built on a P-type substrate.

    o   PMOS: Conducts current (holes) when its gate voltage is low (logic '0'). Built on an N-type substrate (or N-well).

o   Basic Inverter: The fundamental CMOS gate is the inverter. It consists of one PMOS transistor connecting the output to VDD (power supply) and one NMOS transistor connecting the output to VSS (ground).

    o   Input '1': PMOS is OFF, NMOS is ON -> Output is pulled to VSS ('0').

    o   Input '0': PMOS is ON, NMOS is OFF -> Output is pulled to VDD ('1').

o   Key Advantage: In steady state (input is stable '0' or '1'), one of the transistors (either PMOS or NMOS) is always OFF. This means there is ideally no static current path from VDD to VSS, resulting in very low static power consumption. Power is primarily consumed during switching.