pcb design

Manhattan length  —The length of the two sides of a right triangle as a distance between two points, as opposed to the hypotenuse.. (Derived from the Manhattan Alogorithm  for determining the length of a taxicab trip following streets and avenues on the island of Manhattan, NY.)  Routing of traces in orthagonal patterns in a PCB design, or in a semiconductor chip, follows the same pattern as streets and avenues in a city.  The minimum distance between two component leads, or two nodes on a chip, when routing on 90 degrees is the  Manhattan length  .  Advanced PCB auto-routers permit specification of maximum length of classes of nets as a percentage of  Manhattan length  . For example, one could specify clocks as 120% and random nets as 160% of  Manhattan length  . (This percentage, expressed as a ratio, becomes the "Manhattan coefficient", ie. a Manhattan coefficient of 1.2 means the routed length is 120% of the  Manhatten length  .) Specifying such limits on the auto

E-pad  —"Engineering-pad." A plated-through hole or surface mount pad on a PCB placed on the board for the purpose of attaching a wire by soldering. These are usually labeled with silkscreen.  E-pads  are used to facilitate proto-typing, or simply because wires are used for interconnections instead of headers  or terminal block. ECL  —Emitter Coupled Logic.  A type of unsaturated  performed by emitter-coupled transistors.  Higher speeds may be achieved with ECL than are obtainable with standard logic circuits.  ECL  is costly, power hungry, and difficult to use, but it is four times faster than TTL. Electrical Object  —  [Protel]  A graphical object (in a PCB or schematic database) to which an electrical connection can be made, such as a component pin or a wire. Embedded  —(Of a micro-processor(s), or system controlled by such) Dedicated to doing one job or supporting one device and built into the product. EMC  —electromagnetic compatibility.  (1) The abil