Abstract: Modeling of propagation delay and output transition time by use of fitting functions comprised of standard Taylor series and inverse powers is disclosed. These components are used as a basis for generating an equation that predicts circuit performance over a wide range of input transition and output capacitive loads. The present invention includes a computer implemented method for adding functions to the fitting functions or removing functions from the fitting functions until an acceptable error limit has been reached.

Abstract: A method for verifying that an integrated circuit design tool kit has not been modified in an unauthorized manner is accomplished by providing a verification procedure that, when an executable subrule of the tool kit has been selected to be part of the rule system, the executable subrule reads a table of time stamps. This table of time stamps and a key are provided, as representative data, to an authentication subrule by the executable subrule. The executable subrule and the authentication subrule perform an authentication check algorithm upon the representative data to produce remotely and locally checked data respectively. The executable subrule then provides the locally checked data to the authentication subrule which compares the locally checked data with the remotely checked data. When a match occurs between the data, the authentication subrule indicates that the executable subrule has not been modified in an unauthorized manner.

Abstract: An improved differential cascode current push-pull driver is provided by controlling the up level by clamping the collector node with respect to output signal reference VR to less than VCC. The collector resistors are made smaller so there is smaller signal swing and faster operation.

Abstract: A bipolar push-pull driver in which the input transistor is biased so that it does not saturate and the base of its associated output transistor is pulled down to shut off compeletely by a transistor switch controlled by the complimentary output of the other input transistor.