Transmission gate
![Principle diagram of a transmission gate. The control input ST must be able to take to control depending on the supply voltage and switching voltage different logic levels.](/Images/godic/202502/17/Transmission_gate.svg2315.png")
![Two variants of the](/Images/godic/202502/17/Transmission_gate_bowtie_symbol_variants.svg2315.png")
![Resistance characteristic of a transmission gate. VTHN and VTHP denote those positions at which the voltage to be switched has reached a potential, where the threshold voltage of the respective transistor is reached.](/Images/godic/202502/17/Transmission_gate_resistor.svg2315.png")
A transmission gate is similar to a relay that can conduct in both directions or block by a control signal with almost any voltage potential. It is CMOS based switch in which PMOS passes a strong 1 but poor 0 and NMOS passes strong 0 but poor 1. Both PMOS and NMOS work simultaneously.