Application-specific programmable control for high-performance asynchronous circuits

The advantages of the programmable control paradigm are widely known in the design of synchronous sequential circuits: easy correction of late design errors, easy upgrade of product families to meet time-to-market constraints , and modifications of the control algorithm, even at run time. However, de spite the growing interest in asynchronous (self-timed) circuits, programma ble asynchronous controllers based on the idea of microprogramming have not been actively pursued In this paper, we propose an asynchronous microprogr ammed control organization (called a microengine) that targets application- specific implementations and emphasizes simplicity, modularity, and high pe rformance. The architecture takes advantage of the natural ability of self- timed circuits to chain actions efficiently without the clock-based schedul ing constraints that would be involved in comparable synchronous designs. T he result is a general approach to the design of application-specific micro engines featuring a programmable data-path topology that offers very compac t microcode and high performance-in fact, performance close to that offered by automated high-level synthesis tools targeting stare-of-the-art asynchr onous hardwired controllers. In performance comparisons of a CD-player erro r decoder design, the proposed microengine architecture was 26 times faster than the general purpose hardware of a 280 MIPS microprocessor, over three times as fast as the special purpose hardware of a low-power macromodule b ased implementation, and even slightly faster than a finite state machine-b ased implementation.