FET Switches

Field-effect transistor (FET) switches are made of several CMOS transistors. A voltage is applied to the control circuitry, which connects the source (S) and drain (D) of a transistor network (load circuit) as shown in the following figure.

There is no additional isolation between the control circuitry and the signal path, as shown in the following figure. This lack of isolation restricts operation to low voltage, but it allows very fast switching speeds.