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PPT : Asynchronous Chips Seminar with Free Download

Published on April 15, 2016


Slide 1 :



Asynchronous Chips

Slide 2 :


==> Computer chips of today are synchronous.

==> They contain a main clock, which controls the timing of the entire chips.

==> There are problems, however, involved with these clocked designs that are common today

==> New problems with speeding up a clocked chip are just around the corner.

==> Clock frequencies are getting so fast that signals can barely cross the chip in one clock cycle

Slide 3 :


==> Asynchronous, or clock less, design has advantages over the synchronous design

==> The other advantage of a clock less design is power consumption

==> Special light emission measurements of a synchronous chip (left) and an asynchronous chip (right) with the same digital functionality under the same operational conditions indicate hoe much power the chips dissipate

==> Asynhronous chips use power only during computations, while a clocked chip always consumes power because the chip is always running

Slide 4 :

Clockless Chips

==> Figure

Slide 5 :

Asynchronous Logic

==> Data signals may use either “dual rail encoding” or “data building”.

==> Each dual rail encoded Boolean is implemented as two wires.

==> Bundled data has one wire for each data bit and another for timing.

==> Level sensitive circuits typically represent a logic one by a high voltage and a logic zero by a low voltage whereas transition signaling uses a change in the signal level to convey information.

==> The purest form of circuit is delay-insensitive and uses dual-rail encoding with transition signaling.

==> A transition on one wire indicates the arrival of a zero, a transition on the other the arrival of a one

Slide 6 :

Computers Without Clocks

==> Asynchronous chips improve computer performance by letting each circuit run as fast as it can

==>Each part of an asynchronous system may extend or shorten the timing of its steps when necessary, much as a hiker takes long or short steps when walking across rough terrain

==>Asynchronous parts of otherwise synchronous systems are also beginning to appear; the Ultra SPARC IIIi processor recently introduced by SUN includes some asynchronous circuits developed by our group

Slide 7 :

Local Operation

==> A clocked system is like a bucket brigade in which each person must pass and receive buckets according to the tick tock rhythm of the clock.

==> When the clock ticks, each person pushes a bucket forward to the next person down the line.

==> When the clock tocks, each person grasps the bucket pushed forward by the preceding person.

==> Even if most of the buckets are light, everyone in the line must wait for the clock to tick before passing the next bucket

Slide 8 :

Rendezvous Circuits

==> Figure

Slide 9 :

The Need for Speed

==> Research group at Sun Microsystems concentrates on designing fast asynchronous systems.

==> They have found that speed often comes from simplicity.

==> Their initial goal was to build a counter flow pipeline with two opposing data flows – like two parallel bucket brigades moving in opposite directions.

==> They wanted the data from both flows to interact at each of these stages; the hard challenge was to ensure that every “northbound” data element would interact with every “southbound” data element. Arbitration turned out to be essential.

Slide 10 :


==> Clocks have served the electronics design industry very well for a long time, but there are insignificant difficulties looming for clocked design in future.

==> These difficulties are most obvious in complex SOC development, where electrical noise, power and design costs threaten to render the potential of future process technologies inaccessible to clocked design

==> Self-timed design offers an alternative paradigm that addresses these problem areas, but until now VLSI designers have largely ignored it.

==> Things are beginning to change; however, self-timed design is poised to emerge as a viable alternative to clocked design

Slide 11 :



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