The present invention provides a circuitry applied to multiple power domains, wherein the circuitry includes a first circuit block and second circuit block, the first circuit block is powered by a first supply voltage of a first power domain, and the second circuit block is powered by a second supply voltage of a second power domain. The first circuit block includes a first amplifier and a switching circuit. The first amplifier is configured to receive an input signal to generate a processed input signal. When the second circuit block is powered by the second supply voltage, the switching circuit is configured to forward the processed input signal to the second circuit block; and when the second circuit block is not powered by the second supply voltage, the switching circuit disconnects a path between the first amplifier and the second circuit block.