Audio decorrelation is a fundamental building block for immersive audio applications. It has applications in parametric spatial audio coding, audio upmix, audio sound effects and audio rendering for virtual or augmented reality applications. In this paper, we provide insights into the practical design considerations of an audio decorrelator on the example of the decorrelator contained within the upcoming MPEG-I Immersive Audio ISO standard [1]. We describe the desirable properties of such a decorrelator, common approaches for implementation and our particular technology choices for the decorrelator used in MPEG-I for rendering sound sources with homogeneous extent.