A serializer-deserializer instantiated in configurable logic of an integrated circuit is described. The serializer-deserializer includes an input deserializer and an output serializer, which may be commonly coupled via an input/output pad. Each of the serializer and deserializer may be configured for an operating mode selected from a Single Data Rate mode and a Double Data Rate mode. The serializer-deserializer may be used as part of a synchronous interface.