Abstract: An integrated circuit distributed radio frequency oscillator comprises a semiconductor chip which includes a differential input transmission line, a differential output transmission line and, coupled in parallel between these transmission lines at spaced apart portions, a number of differential amplifier cells with adjustable delay. The output end of the output transmission line is coupled back to the input end of the input transmission line by a feedback link with a pair of on-chip capacitors. The delay introduced by the amplifier cells is variable in response to a tuning voltage applied to a differential tuning input, making the oscillator suitable for use as a distributed VCO in, e.g. a phase-locked loop circuit. The layout of the oscillator on a semiconductor chip includes the series-connected arrangement of the differential transmission lines in a rectilinear spiral path.

Abstract: The Model Editor (106) makes simulation modeling easier and more intuitive by extracting essential information and presenting it to the user, and by providing tools to investigate simulation and model robustness, in an interactive, graphical environment. Using the model editor, the user enters relationships or formulas in the equation editor (200), enters symbols in the topology editor (202), and interconnects them (1804). Relationships can be hidden for screen efficiency (1806). Selecting a symbol highlights the corresponding relationships in the equation editor through cross-coupling, and conversely selecting an equation or instance highlights the corresponding symbol in the topology editor (1808). The model editor includes parameter management tools (206) to manage equation parameters. Models or portions thereof that are reused donate the parameter management data to the new model (1810). Following editing and parameter management, the user can perform model robustness and verification.

Abstract: An analysis mechanism is intended for use in a system performance simulator which includes a core simulator and which is intended for simulating the performance of a physical, real-world system, and which operates with a hardware description language. The hardware description language includes representations of physical, real-world devices in the form of a template set, wherein each template in the set includes an extraction mechanism for extracting indicators of system quality from the core simulator for each template, as the simulation progresses, or after simulation is complete. Additionally, a display interface is provided for displaying the system performance indicators of design quality to a designer, either during or after the simulation.

Abstract: A software system that simulates the appearance and operation of a calculator provides a user interface to graphic waveform data base manipulation software. The calculator includes a plural key calculator pad, with the keys in the pad being associable in the system with different vector operators. It also includes a subwindow area in which the symbolically encoded operands and operators that form the expression to be evaluated are maintained for viewing by the user. The calculator's keys, which may be operated by conventional cursor control means, are labeled with a descriptive legend representing the currently assigned operator. A post-fix operand entry protocol resembling that used in conventional scientific calculators is enforced for keypad input, while in-fix notation is used in the subwindow's representation of the expression to be evaluated. The calculator may be used, in conjunction with an interactive simulator, to facilitate the user interface to graphic waveform manipulation software.

Abstract: The instant invention is a system performance simulator which includes a library of expression-literate model artifacts, each of which is at least partially representative, mathematically and operatively, of a model element which includes at least one virtual interface point suitable for operative association with another such point. Assembly means are operatively and disconnectably communicative with the library for accessing selected model artifacts and is capable of understanding the representative expression-literacies characterizing the artifacts, for establishing operative associations between interface points of the artifacts to establish an organized assembly of such artifacts. Means are also provided which are operatively communicative with the assembly means for conducting a performance simulation of such an assembly.

Abstract: A software system that simulates the appearance and operation of a calculator provides a user interface to graphic waveform data base manipulation software. The calculator includes a plural key calculator pad, with the keys in the pad being associable in the system with different vector operators. It also includes a subwindow area in which the symbolically encoded operands and operators that form the expression to be evaluated are maintained for viewing by the user. The calculator's keys, which may be operated by conventional cursor control means, are labeled with a descriptive legend representing the currently assigned vector operator. A post-fix operand entry protocol resembling that used in conventional scientific calculators is enforced for keypad input, while in-fix notation is used in the subwindow's representation of the expression to be evaluated. The calculator may be used, in conjunction with an interactive simulator, to facilitate the user interface to graphic waveform manipulation software.

Abstract: Simulation results enhancement software method and system are disclosed. A partial simulation results data base that is produced by an interactive simulator is software enhanced, using full elemental characterizations from the modeling subsystem thereof, to produce a simulation completion results data base. The simulation completion results data base is suitable for post-simulation processing to enable the viewing or plotting of any dependent variable, or transform thereof, available from the modeling subsystem. A simulation-produced interim results data base provides, in association with a software co-processor, the capability of interrupting the simulation upon the occurrence of a user-defined event. Use of the enhancement software is illustrated in the context of analog circuit simulation, whereby voltage, current and power waveforms are made available to the user without unduly burdening the computer system on which the simulation software is executed.