US 7,606,693 B2Granted

Circuit simulation with decoupled self-heating analysis

AssigneeCadence Design Systems, Inc.

InventorsMin-Che Jeng, Yutao Ma, Zhihong Liu

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Abstract

A solution of a first set of equations of the time-varying electrical response of a circuit is determined between pairs of adjacent time points ti and ti+1 based on predicted electrical responses of the devices at time point ti+1 and as a function of the initial temperatures of the circuit devices at time point ti. A solution of a second set of equations of the time-varying temperature responses of devices of the circuit is determined (1) after each iteration of the first set of equations and as a function thereof or (2) at each time point ti+1 and as a function of the solution of the first set of equations at the time point to determine the corresponding temperature response of the circuit. The solutions of the first and second sets of equations at one or more of the points in time are displayed.

Claims18

Dependent claims

A computer-implemented circuit simulation method comprising:

(a) defining in a computer memory for a circuit a first set of non-linear equations of time-varying electrical responses of devices of the circuit;
(b) defining in the computer memory for the circuit a second set of non-linear equations of time-varying temperature responses of the circuit devices;
(c) storing in the computer memory initial, DC electrical responses of the circuit devices and initial temperatures of the circuit devices;
(d) storing in the computer memory a predicted solution of the first set of equations of the time-varying electrical responses of the circuit devices based on the electrical responses of the circuit devices determined in step (c);
(e) utilizing the most recently predicted solution of the first set of equations as a starting point, solving with a processor of the computer the first set of equations of the time-varying electrical responses of the circuit devices utilizing an iterative solution technique that causes the first set of equations to converge to a new solution of the updated electrical responses of the circuit devices, wherein:
each iteration of the iterative solution technique determines electrical responses of the circuit devices as a function of temperatures of the circuit devices at the commencement of the iterative solution technique;
and
the electrical responses determined in one iteration of the iterative solution technique are utilized as the starting electrical responses for the next iteration of the iterative solution technique until the iterative solution technique converges whereupon the electrical responses of the circuit devices that caused said convergence are deemed to be the updated electrical responses of the circuit devices;
(f) solving once with the processor a linearized form of the second set of equations of the time-varying temperature responses of the circuit devices to determine updated temperatures of the circuit devices, the second set of equations solved as a function of the new solution of the updated electrical responses of the circuit devices determined in step (e);
and
(g) causing a display means to display for each of one or more of the circuit devices (1) at least one of the electrical response and/or (2) the updated electrical response(s) thereof.

8 more elements

A computer system for automatically determining the time-varying electrical and temperature responses of devices of a circuit comprising:

means for storing a first set of non-linear equations of the time-varying electrical responses of devices of a circuit and a second set of non-linear equations of the time-varying temperature responses of the circuit devices;
means for storing initial electrical responses of the circuit devices and initial temperatures of the circuit devices for a point in time t0;
means for storing predicted electrical responses of the circuit devices at each of a plurality of points in time after t0;
means for iteratively solving the first set of equations between each pair of adjacent points in time ti and ti+1 based on the predicted electrical responses of the circuit devices at the point in time ti+1 and as a function of the temperatures of the circuit devices at the commencement of the iterative solution between each pair of adjacent points in time ti and ti+1 such that each iterative solution converges, wherein i=0, 1, 2, . . . , x and x=a desired number of points in time;
means for solving a linearized form of the second set of equations once at each point in time after t0 and as a function of the solution of the first set of equations that resulted in the iterative solution converging at said point in time to determine the corresponding temperature responses of the circuit devices at said point in time;
and
means for displaying for at least one of the points in time the solutions of the first and second sets of equations at said point in time.

4 more elements

A computer-implemented circuit simulation method comprising:

(a) storing in a computer memory for a circuit comprised of a plurality of interconnected circuit devices a first set of non-linear equations of time-varying electrical responses of the circuit devices and a second set of non-linear equations of time-varying temperature responses of the circuit devices;
(b) in the computer memory, initializing the value of a variable n =0;
(c) storing in the computer memory for a time tn initial, DC electrical responses of the circuit devices (x1n) and initial temperatures of the circuit devices (x2n);
(d) in the computer memory, incrementing the value of the variable n by 1;
(e) storing in the computer memory predicted electrical responses of the circuit devices (x1n) for time tn;
(f) utilizing the most recently predicted solution of x1n in step (e) as a starting point, solving with a processing means plural iterations of a Newton-Raphson iteration method on the first set of non-linear equations for x1n until a solution of the Newton-Raphson iteration method on the first set of non-linear equations converges;
(g) as a function of the solution in step (f), solving once with a processing means a linearized form of the second set of non-linear equations for x2n;
(h) repeating steps (d)-(g) until tn=tstop, wherein tstop is a predetermined time after t0;
and
(i) causing a display means to display at least one solution of step (f) and/or at least one solution of step (g).

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/224,249Filed 12 Sep 2005
Published: US 2007/0079205 A15 Apr 2007
Granted: 20 Oct 2009
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

G01R 31/2848
Using hard- or software simulation or using knowledge-based systems, e.g. expert systems, artificial intelligence or interactive algorithms: using…
G06F 30/367
Circuit design at the analogue level: design verification, e.g. using simulation, simulation program with integrated circuit emphasis [SPICE],…
G01R
Measuring electric variables
G06F
Computing and data processing