Modular serializer and deserializer circuits convert a data input in a variety of applications. The serializer includes an array of cells that receive a parallel data input and transfer the word, row by row, to an output buffer that generates a corresponding serial data output. The deserializer includes an input buffer that receives a serial data input and transfers partial words sequentially through an array of cells. When the word fully occupies the cells, the array transmits the word as a parallel data output. A modular clock operates to clock the modular serializer and deserializer.