Diagnosis of discrete event systems in the state-based framework is revisited. State estimation in a diagnoser algorithm is resolved into steps that can be implemented using an interconnected array of simple digital circuits, where control signals and diagnosis can also be computed. Integrating these modules results in a fully hardware realization of a DES diagnoser, whose size scales linearly with the number of plant states. Desirable ¿glitch-free¿ property of the circuit's diagnosis output follows from detailed analysis of the diagnosis algorithm. As a proof of concept, the circuit design is constructed and tested for a simple plant.