The transition to the ATSC 3.0 broadcasting standard is poised to revolutionize the broadcasting industry by integrating broadcast and broadband technologies for enhanced content distribution. This paper presents a reference architecture for implementing ATSC 3.0 workflows in the cloud, facilitating Studio-to-Transmitter Link (STL) over public internet and offering a practical framework for researchers and practitioners. Key features of ATSC 3.0 are highlighted, emphasizing its scalable and flexible cloud-based deployment capabilities. With all components of an ATSC 3.0 system, except the exciter and transmitter, implemented in the cloud, the paper details the architecture’s handling of ROUTE/DASH streams, Physical Layer Pipes (PLPs), and STLTP. It explores dual reception capabilities, allowing receivers to access content from both broadcast and broadband sources simultaneously, and addresses challenges such as CDN overflow and STLTP distribution. The paper evaluates Amazon CloudFront's caching solutions and Automatic Repeat ReQuest (ARQ) protocols, presenting proof-of-concept experiments that validate the feasibility of cloud-based ATSC 3.0 workflows.