This paper presents the first parameterized, SPICEcompatible compact model of a Graphene Nano-Ribbon FieldEffect Transistor (GNRFET) with doped reservoirs, also known as MOS-type GNRFET. The current and charge models closely match numerical TCAD simulations. In addition, process variation in transistor dimension, line edge roughness, and doping level in the reservoirs are accurately modeled. Our model provides a means to analyze delay and power of graphene-based circuits under process variation, and offers design and fabrication insights for graphene circuits in the future. We show that line edge roughness severely degrades the advantages of GNRFET circuits; however, GNRFET is still a good candidate for lowpower applications.