| US 7,493,240 B1 | ||
| Method and apparatus for simulating quasi-periodic circuit operating conditions using a mixed frequency/time algorithm | ||
| Dan Feng, Los Altos, Calif. (US); Joel R. Phillips, Sunnyvale, Calif. (US); and Kenneth Kundert, Los Altos, Calif. (US) | ||
| Assigned to Cadence Design Systems, Inc., San Jose, Calif. (US) | ||
| Filed on May 15, 2000, as Appl. No. 9/570,709. | ||
| Int. Cl. G06F 17/10 (2006.01) | ||
| U.S. Cl. 703—2 [703/14; 703/41; 716/1; 716/6; 716/4] | 38 Claims |
| 1. A computer implemented method for simulating responses of an analog circuit using a mixed frequency time method, the circuit
receiving a periodic sample signal and at least one information signal, the method comprising the steps of:
(a) selecting a set of evenly spaced distinct time points;
(b) defining a set of reference time points, wherein each of the reference time points is associated with one of the distinct
time points;
(c) establishing a first set of relationships between values at the distinct time points and values at the reference time
points, wherein the first set of relationships are defined by a first equation
v−Tc=ΦTc(v−0);
where v−0=vector of signals at distinct time points,
v−Tc=vector of signals at reference time points,
ΦTc=multicycle transition function;
(d) establishing a second set of relationships between the values at the distinct time points and the values at the reference
time points, wherein the second set of relationships are by defined by a second equation
v−nTc=DTc(v−n0);
where v−n0=vector of signals at distinct time points, for boundary condition n,
v−nTc=vector of signals at reference time points, for boundary condition n,
DTc=delay matrix;
(e) combining the first and the second sets of relationships to establish a system of equations in terms of the values at
the distinct time points, wherein combining the first and the second sets of relationships comprises combining the first and
second equations to produce a third equation
(DTcx In)v0−ΦTc(v0)=0,
where x is a Kronecker product and IN is an N by N identity matrix; and
(f) finding responses of the circuit at the distinct time points by solving the established system of equations, as defined
by the third equation.
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