Relative Timing is introduced as an informal method for aggressive asynchronous design. It is demonstrated on three example circuits (C-Element, FIFO, and RAPPID Tag Unit), facilitating transformations from speed-independent circuits to burst-mode, relative timed, and pulse-mode circuits. Relative timing enables improved performance, area, power and testability in all three cases.

This paper describes an investigation of potential advantages and pitfalls of applying an asynchronous design methodology to an advanced microprocessor architecture. A prototype complex instruction set length decoding and steering unit was implemented using self-timed circuits. [The Revolving Asynchronous Pentium ® Processor Instruction Decoder (RAPPID) design implemented the complete Pentium II ® 32-bit MMX instruction set.] The prototype chip was fabricated on a 0.25-CMOS process and tested successfully. Results show significant advantages-in particular, performance of 2.5-4.5 instructions per nanosecond-with manageable risks using this design technology. The prototype achieves three times the throughput and half the latency, dissipating only half the power and requiring about the same area as the fastest commercial 400-MHz clocked circuit fabricated on the same process.

This paper describes an investigation of potential advantages and risks of applying an aggressive asynchronous design methodology to Intel Architecture. RAPPID ("Revolving Asynchronous Pentium® Processor Instruction Decoder"), a prototype IA32 instruction length decoding and steering unit, was implemented using self-timed techniques. RAPPID chip was fabricated on a 0.25µ CMOS process and tested successfully. Results show significant advantages-in particular, performance of 2.5-4.5 instructions/nS-with manageable risks using this design technology. RAPPID achieves three times the throughput and half the latency, dissipating only half the power and requiring about the same area as an existing 400MHz clocked circuit.

Relative timing (RT) is introduced as a method for asynchronous design. Timing requirements of a circuit are made explicit using relative timing. Timing can be directly added, removed, and optimized using this style. RT synthesis and verification are demonstrated on three example circuits, facilitating transformations from speed-independent circuits to burst-mode and pulse-mode circuits. Relative timing enables improved performance, area, power, and functional testability of up to a factor of 3 in all three cases. This method is the foundation of optimized timed circuit designs used in an industrial test chip, and may be formalized and automated.Index Terms-Asynchronous design, dynamic logic circuit, high performance, low-power design, performance tradeoffs.

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