Method and apparatus for steady state analysis of a voltage controlled oscillator
View Patent ↗A computer-implemented method computes the steady-state and control voltage of a voltage controlled oscillator, given a known frequency or a known period of oscillation of the voltage controlled oscillator. Differential algebraic equations representative of the voltage controlled oscillator are generated, where the differential algebraic equations includes a known period or frequency of oscillation and an unknown control voltage of the voltage controlled oscillator. The differential algebraic equations are modified using a finite difference method, a shooting method, or a harmonic balance method, to obtain a set of matrix equations corresponding to the differential algebraic equations. A solution to the matrix equations is obtained using a Krylov subspace method, using a preconditioner for the Krylov subspace method that is derived from a Jacobian matrix corresponding to the matrix equations, where the solution includes the control voltage of the voltage controlled oscillator in steady state.
1. A computer-implemented method of computing a steady state of a voltage controlled oscillator, the method comprising the steps of:
generating a set of one or more differential algebraic equations representative of the of an electronic circuit, for analysis of the voltage controlled oscillator, the set of one or more differential algebraic equations including a known period or a known frequency of oscillation of the voltage controlled oscillator and an unknown control voltage of the voltage controlled oscillator that generates the period or the frequency of oscillation;
modifying the set of one or more differential algebraic equations to obtain a set of one or more matrix equations corresponding to the differential algebraic equations; and
obtaining a solution to the set of one or more matrix equations using a Krylov subspace method, the solution including the control voltage of the voltage controlled oscillator in steady state,
wherein the set of one or more differential algebraic equations is in the form of:
ⅆ
q
(
x
)
ⅆ
t
+
f
(
x
)
+
b
+
ce
=
0
,
where x represents a steady state solution, t represents time, q(x) and f(x) represent parameters of the voltage controlled oscillator that are functions of the steady state solution, b represents an independent source of the voltage controlled oscillator except a control source, and ce represents the control source of the voltage controlled oscillator wherein c is a control voltage scalar and e is a vector with one or two nonzero entries that are either 1 or −1.
2. The computer-implemented method of claim 1 , wherein the set of one or more differential algebraic equations is modified using a finite difference method in time domain to obtain the set of one or more matrix equations.
3. The computer-implemented method of claim 1 , wherein the set of one or more differential algebraic equations is modified using a shooting method in time domain to obtain the set of one or more matrix equations.
4. The computer-implemented method of claim 1 , wherein the set of one or more differential algebraic equations is modified using a harmonic balance method in frequency domain to obtain the set of one or more matrix equations.
5. The computer-implemented method of claim 1 , wherein the step of modifying the set of one or more differential algebraic equations comprises obtaining a Jacobian matrix corresponding to the set of one or more matrix equations, the set of one or more matrix equations being solved using the Krylov subspace method with a preconditioner for the Krylov subspace method being derived at least in part from the Jacobian matrix.
6. A computer system configured to compute the steady state of a voltage controlled oscillator, the computer system comprising:
a model equations storage module storing a plurality of differential algebraic equations corresponding to a plurality of circuit components of the voltage controlled oscillator; and
a circuit simulation engine coupled to the model equations storage module configured to:
generate a set of one or more differential algebraic equations representative of the of an electronic circuit, for analysis of the voltage controlled oscillator, the set of one or more differential algebraic equations including a known period or a known frequency of oscillation of the voltage controlled oscillator and an unknown control voltage of the voltage controlled oscillator that generates the period or the frequency of oscillation;
modify the set of one or more differential algebraic equations to obtain a set of one or more matrix equations corresponding to the differential algebraic equations; and
obtain a solution to the set of one or more matrix equations using a Krylov subspace method, the solution including the control voltage of the voltage controlled oscillator in steady state
wherein the set of one or more differential algebraic equations is in the form of:
ⅆ
q
(
x
)
ⅆ
t
+
f
(
x
)
+
b
+
ce
=
0
,
where x represents a steady state solution, t represents time, q(x) and f(x) represent parameters of the voltage controlled oscillator that are functions of the steady state solution, b represents an independent source of the voltage controlled oscillator except a control source, and ce represents the control source of the voltage controlled oscillator wherein c is a control voltage scalar and e is a vector with one or two nonzero entries that are either 1 or −1.
7. The computer system of claim 6 , wherein the circuit simulation engine modifies the set of one or more differential algebraic equations using a finite difference method in time domain to obtain the set of one or more matrix equations.
8. The computer system of claim 6 , wherein the circuit simulation engine modifies the set of one or more differential algebraic equations using a shooting method in time domain to obtain the set of one or more matrix equations.
9. The computer system of claim 6 , wherein the circuit simulation engine modifies the set of one or more differential algebraic equations using a harmonic balance method in frequency domain to obtain the set of one or more matrix equations.
10. The computer system of claim 6 , wherein the circuit simulation engine obtains a Jacobian matrix corresponding to the set of one or more matrix equations, the set of one or more matrix equations being solved using the Krylov subspace method with a preconditioner for the Krylov subspace method being derived at least in part from the Jacobian matrix.
11. A computer readable medium storing a computer program product configured to perform a computer-implemented method of computing the steady state of a voltage controlled oscillator, the method comprising the steps of:
generating a set of one or more differential algebraic equations representative of the of an electronic circuit, for analysis of the voltage controlled oscillator, the set of one or more differential algebraic equations including a known period or a known frequency of oscillation of the voltage controlled oscillator and an unknown control voltage of the voltage controlled oscillator that generates the period or the frequency of oscillation;
modifying the set of one or more differential algebraic equations to obtain a set of one or more matrix equations corresponding to the differential algebraic equations; and
obtaining a solution to the set of one or more matrix equations using a Krylov subspace method, the solution including the control voltage of the voltage controlled oscillator in steady state,
wherein the set of one or more differential algebraic equations is in the form of:
ⅆ
q
(
x
)
ⅆ
t
+
f
(
x
)
+
b
+
ce
=
0
,
where x represents a steady state solution, t represents time, q(x) and f(x) represent parameters of the voltage controlled oscillator that are functions of the steady state solution, b represents an independent source of the voltage controlled oscillator except a control source, and ce represents the control source of the voltage controlled oscillator wherein c is a control voltage scalar and e is a vector with one or two nonzero entries that are either 1 or −1.
12. The computer readable medium of claim 11 , wherein the set of one or more differential algebraic equations is modified using a finite difference method in time domain to obtain the set of one or more matrix equations.
13. The computer readable medium of claim 11 , wherein the set of one or more differential algebraic equations is modified using a shooting method in time domain to obtain the set of one or more matrix equations.
14. The computer readable medium of claim 11 , wherein the set of one or more differential algebraic equations is modified using a harmonic balance method in frequency domain to obtain the set of one or more matrix equations.
15. The computer readable medium of claim 11 , wherein the step of modifying the set of one or more differential algebraic equations further comprises obtaining a Jacobian matrix corresponding to the set of one or more matrix equations, the set of one or more matrix equations being solved using the Krylov subspace method with a preconditioner for the Krylov subspace method being derived at least in part from the Jacobian matrix.