International Business Machines Corporation

Soroush Abbaspour

Peter Feldmann

Debjit Sinha

Chandramouli Visweswariah

Gregory M Schaeffer

Adil Bhanji

Ayesha Akhter

Safar Hatami

David James Hathaway

Vladimir P Zolotov

Peter Anton Habitz

Ruchir Puri

Jinjun Xiong

Joachim Keinert

David J Widiger

Sampath Dechu

Gary S Ditlow

Hemlata Gupta

Chandramouli V Kashyap

Harry John Beatty, Iii

Jeffrey Mark Ritzinger

Revanta Banerji

Ratan Singh

David Ling

A method for accurately performing a timing, power, and noise analysis by pre-processing the characterization points of the available libraries, storing time consuming parts of the analysis and utilizing the pre-processed information during active runs to calculate the attributes at a desired PVT point. The PVT space is preferably sub-divided into triangular or rectangular regions, preferably obtained using Delaunay triangulation. In one embodiment, the invention performs an up-front pre-processing step on the characterized libraries to compute the static portion of the interpolation function that is independent of the specific instance; and a coefficient matrix that allows for interpolation of specific instances.

Method for supporting multiple libraries characterized at different process, voltage and temperature points

A system, method and computer program product for modeling a semiconductor device structure. The system and method implemented includes performing a simulation of the circuit by applying at least one input waveform on a circuit input port, and loading an output port with at least one of output load; determining, at successive time steps of the circuit simulation, a voltage value Vi on the input port, a voltage value Vo on the output port, and a current values (ia) and (ib) on the respective input and output ports. Then there is computed from the respective current value for each successive time step of the simulation, at least one charge value (Qa(Vi, Vo)) and (Qb(Vi, Vo)), respectively, as a function of Vi and Vo voltage values; and generating a nonlinear charge source from the at least one charge value, the nonlinear charge source used in modeling a dynamic behavior of the cell. A voltage controlled charge source (VCCS) is thereby determined by capturing the natural digital circuit cell behavior.

Characterization of nonlinear cell macro model for timing analysis

A computer-implemented system, method, and storage device simulate a periodic voltage waveform in a network model of the integrated circuit design. The method then determines resultant current values in each segment of nets of the integrated circuit design resulting from the periodic voltage waveform and performs a Fourier transform of the periodic voltage waveform to generate a frequency domain representation of the periodic voltage waveform. The frequency domain representation comprises multiple Fourier terms, each of the Fourier terms is a frequency that is a multiple of the base frequency. Next, the method performs an AC analysis of the resultant voltage at each frequency of the multiple Fourier terms. The AC analysis provides an electrical current value for each of the frequencies of the Fourier terms for each of the nets. This allows the method to compute a root mean square current through each of the nets based on the AC analysis. Then, the method determines whether the root mean square current for any of the segments of the nets exceeds a current limit, and reports any segment of the nets for which the root mean square current exceeds the current limit.

Performing reliability analysis of signal wires

A system and method for waveform compression includes preprocessing a collection of waveforms representing cell and/or interconnect response waveforms and constructing a representative waveform basis using linear algebra to create basis waveforms for a larger set of waveforms. The collection waveforms are represented as linear combination coefficients of an adaptive subset of the basis waveforms to compress an amount of stored information needed to reproduce the collection of waveforms. The representation of coefficients may be further compressed by, e.g., analytic representation.

Efficient compression and handling of model library waveforms

In one embodiment, the invention is a moment-based characterization waveform for static timing analysis. One embodiment of a method for mapping a timing waveform associated with a gate of an integrated circuit to a characterization waveform includes using a processor to perform steps including: computing one or more moments of the timing waveform and defining the characterization waveform in accordance with the moments.

Moment-based characterization waveform for static timing analysis

A method for optimizing a circuit includes at least a first branch and a second branch includes defining an objective function using a shape of waveforms measured at a timing point in each branch, and optimizing the objective function to minimize a variance of clock skew of the first branch and the second branch across different process voltage temperature values.

Method and system for optimizing a device with current source models

An abstraction model supporting multiple hierarchical levels is inputted into a generalized static timing analysis of a hierarchical IC chip design to analyze and optimize the design of circuits integral to the chip containing a plurality of macro abstracts. An electrical network, synthesized for an internal abstract interconnect segment, is performed only once per macro and is applied to multiple instances of the macro abstract model in the IC chip design. The synthesized electrical network is a resistive capacitive or a resistive inductive capacitive network or a combination thereof. The synthesized electrical network is then used to match impulse response transfer functions of the network and the abstract interconnect segment's timing model. This network is stitched with the electrical parasitics of external interconnect segments connected to macro primary outputs. Various model order reductions are then performed on the electrical parasitics of external interconnects prior to network stitching. A static timing analysis is performed on the final network.

Method of performing static timing analysis considering abstracted cell's interconnect parasitics

A method and system to improve the performance of an integrated circuit (IC) chip by removing timing violations detected by performing a statistical timing analysis, given distributions of process and environmental sources of variation. The distributions are quantized using a minimum distortion criterion into discrete values. For each timing node of the IC circuit, a discrete minimum and maximum operation is performed on the timing parameters using a subset of combinations of the discrete values. The results of the discrete minimum and maximum operation are then de-quantized and propagated to a subsequent timing node and edge thereof. The process continues until one or more primary inputs and outputs of the IC chip are reached. The design of the IC chip is modified by removing all the timing violations identified.

Order independent method of performing statistical N-way maximum/minimum operation for non-Gaussian and non-linear distributions

A method for converting interconnect parasitics of an interconnect network into slew dependent pin capacitances utilizes charge matching between predetermined voltage thresholds. During timing abstraction of a macro, parasitics of interconnects connected to the primary inputs are represented as slew dependent pin capacitances in an abstract model being created. Interconnect model order reduction is employed to speed the process. The generated abstract is subsequently used in place of each occurrence of the macro during chip level hierarchical static timing analysis, leading to an enhanced accuracy of the timing analysis of the logic components driving the abstracts.

Method of employing slew dependent pin capacitances to capture interconnect parasitics during timing abstraction of VLSI circuits

An approach for performing multiple voltage threshold timing analysis for a digital integrated circuit is described. In one embodiment, there is a multiple voltage threshold timing analysis tool for performing a multiple voltage threshold timing analysis of a digital integrated circuit having at least one logic gate loaded by an interconnect circuit. In this embodiment, a characterization data retrieving component is configured to obtain characterization data describing driving behavior of the at least one logic gate. An interconnect circuit model retrieving component is configured to obtain a model of the interconnect circuit. A multiple voltage threshold timing analysis component is configured to derive a sequence of crossing times for the driving point voltage waveform to advance between successive voltage thresholds. The multiple voltage threshold timing analysis component also generates a voltage waveform from the derived sequence of crossing times.

Multiple voltage threshold timing analysis for a digital integrated circuit

An approach for performing arbitrary waveform propagation through a logic gate using timing analysis results is described. In one embodiment, there is an arbitrary waveform propagation tool for determining an effect of noise on a digital integrated circuit having at least one logic gate. A timing analysis component is configured to perform a timing analysis on the at least one logic gate and a noise analysis component is configured to perform a noise analysis. A waveform propagation model synthesizer component is configured to dynamically synthesize a waveform propagation model as a function of the timing analysis. The waveform propagation model synthesizer component is further configured to apply an arbitrary voltage waveform comprising one of a noisy waveform or noise glitch waveform and determine an effect of the arbitrary voltage waveform on the at least one logic gate from the dynamically synthesized waveform propagation model.

Arbitrary waveform propagation through a logic gate using timing analysis results

An approach that represents and propagates a variational voltage waveform in statistical static timing analysis of digital circuits is described. In one embodiment, there is a statistical static timing analysis tool for analyzing digital circuit designs. The statistical static timing analysis tool includes a variational waveform modeling component that is configured to generate a variational waveform model that approximate arbitrary waveform transformations of waveforms at nodes of a digital circuit. The variational waveform model transforms a nominal waveform into a perturbed waveform in accordance with a plurality of waveform transformation operators that account for variations that occur between the nominal waveform and the perturbed waveform. A variational waveform propagating component is configured to propagate variational waveforms through a timing arc from at least one input to at least one output of the digital circuit in accordance with the variational waveform model.

Representing and propagating a variational voltage waveform in statistical static timing analysis of digital circuits

An accurate method to compute the capacitance at a pin whose capacitance is slew dependant. The method uses existing library characterized data and provides an equation based approach which can easily be integrated in static timing analysis without the added resource needs that an iterative approach would require. An RC/RLC network from slew and output load dependent pin capacitance tables is generated. The resulting linear network which models the pin capacitance is then stitched to the original interconnect network and used to calculate the propagation delay across a gate and corresponding interconnect. The method steps include: a) determining a response of the gate pin capacitance to its input slew and output load; b) synthesizing a linear time-invariant filter that matches the response; c) extending the interconnect model to include the synthesized time-invariant filter; and d) inputting the extended interconnect model into a static timing analysis for determining timing behavior between a gate input and each of its fan-out gates.

Method of modeling and employing the CMOS gate slew and output load dependent pin capacitance during timing analysis

In one embodiment, the invention is a method and apparatus for static timing analysis in the presence of a coupling event and process variation. One embodiment of a method for computing a statistical change in delay and slew due to a coupling event between two adjacent nets in an integrated circuit design includes conducting a statistical timing analysis of the integrated circuit design, computing a statistical overlap window between the adjacent nets, where the statistical timing window represents a period of time during which signals on the adjacent nets can switch contemporaneously and computing the statistical change of delay due to the coupling event, in accordance with the statistical overlap window.

Method and apparatus for static timing analysis in the presence of a coupling event and process variation

A preliminary static timing analysis run is performed to calculate the delay and slew as well as timing windows for each net in the design, followed by coupling analysis for each given aggressor-victim combination, and to calculate the noise effect on the timing of victim net. Given a set of functional groups that relate the coupled aggressors to each other, the worst set of aggressors are calculated that satisfy the constraints from the functional groups, based on the calculated impact of each aggressor on the victim. Similarly the set of aggressors which contribute to the maximum amount of inductive coupling noise effect on timing are calculated. Furthermore, the coupling noise impact of the reduced set of aggressors on the given victim line and adjust the delay value calculated in the preliminary static timing analysis run.

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Fishkill, NY, United States of America

Soroush Abbaspour