Fifo apparatus for the boundary of clock trees and method thereof

Abstract

A FIFO apparatus uses a first clock signal in a first clock domain to receive an input signal and uses a second clock signal in a second clock domain to output an output signal. An example apparatus includes: at least three write registers belonging to the first clock domain for receiving the input signal. Each of the write registers has a first output. A first controller belonging to the first clock domain enables the registers, in accordance with an order, to generate an initial signal. A multiplexer receives the first outputs. A second controller belonging to the second clock domain, receives the initial signal through an asynchronous interface and controls the multiplexer to output the first outputs in accordance with the order to be the output signal, wherein the second clock domain is a clock tree generated based on the first clock domain.