Static CMOS is a logic circuit design technique whereby the output is always strongly driven due to it always being connected to either V_cc or GND (except when switching). This design is in contrast to Dynamic CMOS which relies on the temporary storage of signal using various load capacitances.

Overview

A static CMOS circuit is composed of two networks:

• pull-up network (PUN) - a set of PMOS transistors connected between V_cc and the output line
• pull-down network (PDN) - a set of NMOS transistors connected between GND and the output line

Components designed out pull-up and pull-down networks operate in a mutually exclusive way; in a steady state there is never a direct path between V_cc and GND. Devices that are made up of PUN/PDN are always strongly driven and therefore offers strong immunity from noise.