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Show 12 Abbreviating the Computation The process for manufacturing integrated circuits will impose common values on such variables as interconnect thickness and path width. These are values often derived from a technology file, and may be factored into an equation before it is used in the compute intensive portions of the ACRE methodology to abbreviate the computation. This is the step of taking an equation and building a table by inserting those values known before hand. Where path thickness and path width are factors in an equation but where they are constant for a layout, they may be included in a table before it is used to evaluate layout. This might be called compiling an equation into ACRE. Voltages Determined from Resistance and Capacitance On a silicon substrate in a traditional five volt circuit a glitch introduced by cross-talk of 0. 7 volt or more is potentially disastrous because that will turn on a gate and introduce an erroneous state into the logic. When the driving voltages are lower, some other value equal to the diode threshold voltage represents the disaster voltage; that threshold when a gate may have its state changed by a voltage spike from a signal through some coupling capacitance or inductance. Three factors interplay to cause the cross-talk to be increased, and they are explained in terms of silicon technology although they apply to any technology. First is the dv I dt of the signals in the circuit; the steeper the edges then the more crosstalk they introduce into the circuit. Second is the amount of coupling capacitance, and third is the conductance of the lines and the terminations, |
