asynchronous logic

(redirected from Asynchronous circuit)
Also found in: Wikipedia.

asynchronous logic

[ā′siŋ·krə·nəs ′läj·ik]
(electronics)
A logic network in which the speed of operation depends only on the signal propagation through the network.

asynchronous logic

(architecture)
A data-driven circuit design technique where, instead of the components sharing a common clock and exchanging data on clock edges, data is passed on as soon as it is available. This removes the need to distribute a common clock signal throughout the circuit with acceptable clock skew. It also helps to reduce power dissipation in CMOS circuits because gates only switch when they are doing useful work rather than on every clock edge.

There are many kinds of asynchronous logic. Data signals may use either "dual rail encoding" or "data bundling". Each dual rail encoded Boolean is implemented as two wires. This allows the value and the timing information to be communicated for each data bit. 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 signalling uses a change in the signal level to convey information. A speed independent design is tolerant to variations in gate speeds but not to propagation delays in wires; a delay insensitive circuit is tolerant to variations in wire delays as well.

The purest form of circuit is delay-insensitive and uses dual-rail encoding with transition signalling. A transition on one wire indicates the arrival of a zero, a transition on the other the arrival of a one. The levels on the wires are of no significance. Such an approach enables the design of fully delay-insensitive circuits and automatic layout as the delays introduced by the layout compiler can't affect the functionality (only the performance). Level sensitive designs can use simpler, stateless logic gates but require a "return to zero" phase in each transition.

http://cs.man.ac.uk/amulet/async/.
References in periodicals archive ?
By using asynchronous circuit design, the chip is event-driven--only consuming power when it needs to--and is fabricated in a low-power CMOS process.
For implementation in FPGA, Balsa creates a file compatible with a Verilog specification for each asynchronous circuit.
Sequential circuit is of two types namely synchronous and asynchronous circuit.
Added to this edition are materials on CMOS logic; modern two-level and multi-level logic synthesis methods; logic design for emerging nanotechnologies; test generation, design for testability, and built-in self-test for combinational and sequential circuits; and modern asynchronous circuit synthesis techniques, among other recent topics.
quellas afiliadas al ACiD-WG (Working Group on Asynchronous Circuit Design) y quienes siguen la pista de la tecnologia pero no tienen un esfuerzo visible en investigacion
Asynchronous circuits are those which do not consider any quantization of time.
The themes are model transformations, concurrent system verification, conformance and run-time techniques, stochastic systems, asynchronous circuits, synchronous and heterogeneous systems, and timed systems.
International Symposium on Asynchronous Circuits and Systems (16th: 2010: Grenoble, France)

Full browser ?