CMOS Analogue Switches—Structure and Specifications

CMOS analogue switches are the solid state equivalent of mechanical switches (toggle, pushbutton and relay). Unlike their mechanical equivalents, CMOS analogue switches have no moving parts and are free of contact bounce, contact deterioration, and fatigue induced lifetime limits. CMOS switches require very low power to operate, are able to switch in tens of nanoseconds or faster, and naturally support analogue swings up to and including the power rails.

Unlike their mechanical equivalents, CMOS analogue switches have variable on resistance, temperature sensitive leakage currents, and significant current handling limits. This paper provides an overview of analogue switch structure, operation, and the designer specifications that are used to describe the overall operation.