SYSTEM AND METHOD FOR FAST POWER GRID AND SUBSTRATE NOISE SIMULATION
Systems and methods related to fast simulation of power supply networks and identification of a set of extrema (e.g., maxima or minima) waveforms associated with the power supply networks. In accordance with an embodiment, a method is provided for simulating an electrical circuit, comprising preselecting an input vector file, initializing a supply voltage to a fixed value, performing event driven simulation using the input vector file, so as to extract time-varying power supply current waveforms at a plurality of power grid points. The method also comprises simulating a power grid using a linear network simulator or other SPICE type simulation tool, so as to derive time-varying voltage waveforms from the current waveforms for each point on the power grid. The method further comprises comparing current and/or voltage waveforms with a previous simulation; and repeating the above steps from event driven simulation onwards, using a function of voltage waveforms from previous simulations, until the values of current and/or voltage waveforms converge within a pre-specified tolerance, or an iteration limit has been reached.
1 . A method for simulating an electrical circuit, comprising:
preselecting an input vector file;
initializing a supply voltage to a fixed value;
performing event driven simulation using the input vector file, so as to extract time-varying power supply current waveforms at a plurality of power grid points;
simulating a power grid using a linear network simulator or other SPICE type simulation tool, so as to derive time-varying voltage waveforms from the current waveforms for each point on the power grid;
comparing current and/or voltage waveforms with a previous simulation; and
repeating the above steps from event driven simulation onwards, using a function of voltage waveforms from previous simulations, until
the values of current and/or voltage waveforms converge within a pre-specified tolerance, or
an iteration limit has been reached.
2 . The method of claim 1 wherein the function of voltage waveforms is a weighted average of voltage values at each time step.
3 . The method of claim 1 wherein the model of the power grid is an R, RC, RL, RLC or RLCK circuit.
4 . The method of claim 1 wherein each event in the event driven simulation is defined in a data structure which includes parameters characterizing the state of a node in the circuit associated with that event and a start time and end time of the event.
5 . The method of claim 4 wherein if multiple events are defined for the same node in the circuit then:
determining if the multiple events occur substantially simultaneously based on their start and end times;
collapsing the substantially simultaneous events into one event; and
selecting a new event from a library of events that characterizes the substantially simultaneous events.
6 . The method of claim 5 further comprising:
determining if the multiple events result in a glitch;
applying electrical masking to the glitch.
7 . The method of claim 1 wherein for each iteration, analyzing a previous event and modifying a current event based on the output characteristics of the previous event.
8 . The method of claim 1 wherein if the current and voltage waveforms do not converge then obtaining current waveforms from a new event driven simulation, applying these to their corresponding points and resimulating the power grid.
9 . The method of claim 1 wherein substrate current waveforms are extracted at a plurality of substrate points after the final iteration and are used for analyzing noise distribution in an integrated circuit (IC) substrate, by simulating the substrate current waveforms along with a model of the IC substrate in a linear network simulator or similar SPICE type tool.
10 . The method of claim 9 wherein the model of the IC substrate can be an R or RC model.
11 . A system for simulating an electrical circuit, comprising:
a computer, including a computer readable medium and processor operating thereon; and
a simulation tool, executing on the computer, wherein the simulation tool is operable to
preselect an input vector file;
initialize a supply voltage to a fixed value;
perform event driven simulation using the input vector file, so as to extract time-varying power supply current waveforms at a plurality of power grid points;
simulate a power grid using a linear network simulator or other SPICE type simulation tool, so as to derive time-varying voltage waveforms from the current waveforms for each point on the power grid;
compare current and/or voltage waveforms with a previous simulation; and
repeat the above steps from event driven simulation onwards, using a function of voltage waveforms from previous simulations, until
the values of current and/or voltage waveforms converge within a pre-specified tolerance, or
an iteration limit has been reached.
12 . The system of claim 9 wherein the function of voltage waveforms is a weighted average of voltage values at each time step.
13 . The system of claim 9 wherein the model of the power grid is an R, RC, RL, RLC or RLCK circuit.
14 . The system of claim 9 wherein each event in the event-driven simulation is defined in a data structure which includes parameters characterizing the state of a node in the circuit associated with that event and a start time and end time of the event.
15 . The system of claim 14 wherein if multiple events are defined for the same node in the circuit then:
determining if the multiple events occur substantially simultaneously based on their start and end times;
collapsing the substantially simultaneous events into one event; and
selecting a new event from a library of events that characterizes the substantially simultaneous events.
16 . The system of claim 15 further comprising:
determining if the multiple events result in a glitch;
applying electrical masking to the glitch.
17 . The system of claim 11 wherein for each iteration, analyzing a previous event and modifying a current event based on the output characteristics of the previous event.
18 . The system of claim 11 wherein if the current and voltage waveforms do not converge then obtaining current waveforms from a new event driven simulation, applying these to their corresponding points and resimulating the power grid.
19 . The system of claim 11 wherein substrate current waveforms are extracted at a plurality of substrate points after the final iteration and are used for analyzing noise distribution in an integrated circuit (IC) substrate, by simulating the substrate current waveforms along with a model of the IC substrate in a linear network simulator or similar SPICE type tool.
20 . The system of claim 11 wherein the model of the IC substrate can be an R or RC model.