Analog switches are CMOS components with which switching functions are executed. They are functionally comparable to relays
and can have one or more switching contacts. The switching contacts of a switch
aredesignated as normally open and normally closed, whereby the normally open contact is closed in the rest position and the normally closed contact is open. The contacts are only activated by corresponding control signals. In terms of labelling, an analogue switch with four individually actuated NO contacts is called a 4x1 NO contact. If, on the other hand, four NO contacts are switched by a common control input, such an analogue switch is called 1x4 NO contact. The same applies to normally closed contacts or combinations of normally closed contacts and normally open contacts.
Important characteristics of analog switches are the on-resistance, the crosstalk and its attenuation, the switching times, which are in the nanosecond range, and the permissible switching current.