Transmission gate
A transmission gate (TG) is an analog gate similar to a relay that can conduct in both directions or block by a control signal with almost any voltage potential. It is a CMOS-based switch using a p-channel MOSFET (PMOS) that passes a strong 1 but a poor 0, and a n-channel MOSFET (NMOS) that passes a strong 0 but a poor 1.