A transmission gate self-biases its transistors to provide a constant gate biasing that provides a consistent path for an input signal to be cleanly passed to the gate's output and protects the transistors' gate oxide in cases of high input signals. An array of matched transistors are arranged to be biased by a voltage input node and with a current source configured to provide a bias current across individual transistors of the array of matched transistors. A current sink is configured to sink the bias current across the individual transistors to set a bias voltage at a voltage input node to a multiple of a gate-to-source voltage for the individual transistors of the array of matched transistors. A different set of transistors is configured to provide a signal path for an analog input signal.