A circuit comprises a first circuit and a second circuit. The first circuit is configured to operate at a first-circuit supply voltage value, and to generate a first reference voltage value based on a voltage rated for transistors in a second circuit. The second circuit is configured to operate at a second-circuit supply voltage value, to receive a first signal and the first reference voltage value, and to clamp an input node of the second circuit based on the first reference voltage value. The second-circuit supply voltage value is less than the first-circuit supply voltage value. The first signal is configured to swing between a low voltage value and a voltage value higher than the second-circuit supply voltage value.